MORTEX G18D SERIES Guide

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USERS INFORMATION MANUAL
DOWNFLOW ONLY For Installation In:
SINGLE STAGE GAS FIRED FURNACE 1. Manufactured (Mobile) Home 2. Recreational Vehicle
MODELS: G18D SERIES 3. Modular Homes & Buildings
LIST OF SECTIONS – USERS INFORMATION MANUAL
1 -Safety 1 3 - Start Up and Shutdown Instructions 6
2 - Owners Information and Seasonal Information 5 4 - Owner Maintenance 7
LIST OF SECTIONS – SERVICE AND MAINTENANCE MANUAL
1 – Safety 9 5 - Trouble Shooting 17
2 - Furnace Maintenance 10 6 - Blower Performance 18
3 - Furnace Operation 15 7 – Accessory and Replacement Parts List 18
4 - Sequence of Operation 15 8 - Wiring Diagrams 21
LIST OF FIGURES
1 - Component Locations 4 12 – Four (4) Inch Combustion Air Tube Flange 12
2 – Burner Flame Drawing 4 13 – Flue Box Cover Screws 12
3 – Furnace Examination 5 14 – Flue Box Assembly 12
4 – WR 36J Gas Valve 7 15 – Combustion Air Assembly 13
5 – Gas Supply Line Shutoff Valve Location 7 16 – Blower Assembly 14
6 – Return Air Filter Locations (Outside View) 8 17 – Component Locations 14
7 - Return Air Filter Locations (Inside View) 8 18 – Integrated Control Board 17
8 – Burner Assembly 10 19 – White Rodgers 36J Gas Valve 18
9 - Burner Assembly, Support Plate Retaining Screws & Orifices 11 20 - Replacement Parts Item Identification 19
10 – Heat Exchanger Assembly w/ Dimples 11 21 - Wiring Diagram – Heating Only Models 21
11 – Top Cover Screws and Combustion Air Pan Screws 12 22 – Wiring Diagram – A/C Ready Models 22
LIST OF TABLES
1 –Inlet Gas Pressure Range 18 4 - Accessory Parts List 18
2 – Manifold Gas Pressure 18 5 – Replacement Parts List 20
3 – Blower Performance – 10 x 8 Blower 18
CONTACT INFORMATION
 Contact us by mail: Manufactured and Distributed by Mortex Products Inc Web Page
501 Terminal Rd www.mortx.com
Fort Worth, TX 76106
SECTION I: SAFETY
SAFETY SYMBOLS AND SIGNAL WORDS
This is a safety alert symbol. When you see this symbol on
labels, or in manuals, be alert to the potential for personnel injury
Understand and pay particular attention to the signal words
DANGER, WARNING or CAUTION.
DANGER: indicates an imminently hazardous situation, which
if not avoided, will result in death or serious injury.
WARNING: indicates a potentially hazardous situation, which
if not avoided, could result in death or serious injury.
CAUTION: indicated a potentially hazardous situation, which
if not avoided, may result in minor or moderate injury. It is
also used to alert against unsafe practices and hazards involving
property damage.
Home owners and / or furnace users must read all
instructions in this manual before performing any
maintenance on this furnace. This manual must be
saved for future reference.
 
-Do not store or use gasoline or other flammable vapors
and liquids in the vicinity of this or any other
appliance.
-
-WHAT TO DO IF YOU SMELL GAS:
-
Do not try to light any appliance.
Do not touch any electrical switch. Do not use any
phone in your building, including cell phones.
Leave building immediately.
Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
If you cannot reach your gas supplier, call the fire
department.
Instruction and service must be performed by a
qualified installer, service agency or gas supplier.

WARNING:
FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly could
result in serious injury, death, or property
damage.

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Safety Requirements
Potently hazardous situations described in the manual require
that additional safety precautions be taken.
1. The furnace area must be kept clear and free of combustible
materials, gasoline and other flammable vapors and liquids.
2. Insulating material may be combustible. The furnace must
be kept free and clear of insulating material. The furnace
area must be examined when the furnace is installed in an
attic or other insulated space or when insulation is added to
make sure that insulation has been kept away from the
furnace.
3. The furnace needs air for combustion in order to operate
properly and safely. Do not block or obstruct air openings on
the furnace, air openings to the area where the furnace is
installed, or spaces around the furnace.
4. Follow the instruction exactly as shown on the operating
instructions label, or the startup and shutdown instructions
located on page 3 of this manual, to properly start the
furnace or turn the furnace off.
5. Should the gas supply fail to shut off or if overheating
should occur shut off the manual gas valve located on the
gas pipe before turning off the electrical power supply to the
furnace. Refer to Figure 5.
6. Do not use this furnace if any part has been under water, a
flood damaged furnace is extremely dangerous. Attempts to
use the furnace could result in a fire or explosion. A
qualified service agency should be contacted to inspect the
furnace and replace all gas controls, control system parts,
and electrical parts that have been wet. In some cases the
damage may be so severe that the furnace may need to be
replaced
7. Flammable materials, solvents or other volatile liquids
should be stored only in approved containers outside your
home. These materials vaporize easily and are extremely
dangerous.
8. Do not store cleaning materials near your furnace. Materials
such as bleaches, detergents, powdered cleaners, etc. can
cause corrosion of the heat exchangers causing premature
failure.
9. Do not use the area around the furnace as a storage area for
items that could block the normal flow of air to the furnace.
This flow of air is required for ventilation of the various
furnace components.
FIRE OR EXPOLSION HAZARD
This furnace is designed and approved for use with Natural
Gas and (LP) Propane Gas ONLY. Do not burn any liquid
fuel or solid fuel in this furnace.
Burning any unapproved fuel in this furnace will result in
damage to the furnace heat exchanger, which could result in
a fire, personal injury, property damage and / or loss of life.
Burning any unapproved fuel in the furnace will result
immediate termination of the factory warranty.
Any adjustment, service or maintenance by the home owner
and / or user may create a condition where the operation of
the product could cause personal injury or property damage.
Only qualified service personnel, a contractor, or an installer
may refer to the service and maintenance section of this
manual for assistance or for additional information on this
appliance.
This product requires periodic routine maintenance and
cleaning of the exterior surfaces by the homeowner or user
to remove dust and debris. Any additional service must be
performed by qualified personnel. This appliance must be
serviced and maintained as specified in these instructions
and / or to any applicable local, state, and national codes
including, but not limited to building, electrical, and
mechanical codes.
FIRE OR ELECTRICAL HAZARD
Failure to follow the safety warnings exactly could result in
serious injury, death, or property damage.
A fire or electrical hazard may result causing property
damage, personal injury or loss of life.
ELECTRICAL OR EXPLOSION HAZARD
Do not use this furnace if any part has been under water.
A flood damaged furnace is extremely dangerous. Attempts
to use the furnace can result in a fire.
A qualified contractor, installer, or service agency must be
contacted to inspect the furnace for any water damage and
replace all components, control system parts, or electrical
parts that have been damaged. If enough damage is present,
the furnace may need to be replaced
USE ONLY NATURAL GAS OR HD-5 PROPANE FUEL IN
THIS FURNACE.
DO NOT USE “COMMERCIAL GRADE PROPANE” OR
ANY PROPANE BLEND OTHER THAN HD-5.
IF A FUEL OTHER THAN NATURAL GAS OR HD-5
PROPANE IS USED IN THIS FURNACE YOUR
WARRANTY WILL BE VOID.

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COMBUSTION AIR QUALITY
(LIST OF CONTAMINANTS)
This furnace will require outdoor air for combustion. This
furnace cannot be exposed to any of the following environments:
Restricted Environments.
Buildings with indoor pools.
Furnaces installed in laundry rooms.
Furnaces installed in hobby or craft rooms.
Furnace installed in chemical storage areas.
Chemical Exposure.
This furnace will require outdoor air for combustion. The
furnace cannot be exposed to the following substances and/or
chemicals.
Permanent wave solutions.
Chlorinated waxes or cleaners.
Chlorine based swimming pool chemicals.
Water softening chemicals.
De-icing salts or chemicals.
Carbon tetrachloride.
Halogen type refrigerants.
Cleaning solvents – such as perchloroethylene.
Printing inks, paint removers, varnishes, ECT.
Hydrochloric acid.
Cements and glues.
Antistatic fabric softeners.
Masonry acid washing materials.
When outdoor air is used for combustion, the combustion air
intake pipe termination must be located external to the building
and in an area where there is no exposure to the substances listed
above. Any exposure to the substances listed above will void
your warranty.
Appliances must not be installed where they may be
exposed to potentially explosive or flammable atmosphere.
Installing this appliance in an explosive or flammable
atmosphere will result in a fire or explosion causing
personnel injury, property damage and / or death.
Appliances must not be installed where they may be
exposed to potentially explosive or flammable atmosphere.
Installing this appliance in an explosive or flammable
atmosphere will result in a fire or explosion causing
personal injury, property damage and/or death.
Because of the potential of odorant fade, a gas leak may not
be detected by smell. It is recommended that black iron pipe
be used from the gas valve to outside the home in order to
prevent gas leaks inside the home. Copper and brass tubing
and fittings (except tin lined) shall not be used if the gas
contains more than a trace (0.3 grains per 100 cubic ft.) of
hydrogen sulfide gas. Check with your gas supplier about
gas content and for a gas leak detector.
To prevent premature heat exchanger failure, do not locate
any gas-fired appliances in area where corrosive vapors are
present in the atmosphere. Refer to Section I
COMBUSTION AIR
Q
UALITY.
DO NOT wet electronic components or wire connections
during the leak test. Wetting electronic components may
damage circuitry and to the wire connections and can cause
a hazardous situation.
Dry moisture from all leads and terminals if wetting occurs.
Wait at least 12 hours for the electronic components and
wire connections to fully dry before energizing the system.
IMPORTANT
This furnace area must never be used as a broom closet, for
any other storage purposes or allow the furnace to come in
contact with the following substances.
1. Spray or aerosol cans, rags, brooms, dust mops, vacuum
cleaners, or other cleaning tools.
2. Soap powders, bleaches, waxes, other cleaning
compounds, plastic items or containers
3. Gasoline, kerosene, cigarette lighter fluid, dry cleaning
fluids, or other volatile fluids.
4. Paper bags, boxes, or other paper products.
HAZARD OF ASPHYXIATION: Negative pressure
inside the closet with closet door closed and the furnace
blower operating cannot be more negative than minus 0.05
inwc.
CARBON-MONOXIDE POISNING HAZARD
Failure to follow instructions could result in severe
personal injury or death due to carbon-monoxide
poisoning.
Check that all openings in the outside wall around the
vent (and air intake) pipes are sealed to prevent
infiltration of combustion products into the building.
Check that the furnace vent (and air intake) terminals
are not obstructed in any way during all seasons.

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FIGURE 1: Component Locations
INSTRUCTIONS FOR EXAMINING THE FURNACE
It is the owner’s responsibility to ensure that an annual inspection
of the entire heating portion of the furnace is made by a qualified
service agency. Examine the furnace as outlined below in steps
below before each heating season.
1. Examine the heat exchanger, vent pipe, combustion air
passages, vent connectors and chimney to be sure they are
clear and free of obstructions.
2. Examine the vent pipe making sure it is firmly in place, that
it is attached to the top of the furnace and it is physically
sound without holes and all of the connections are secure.
3. Examine the return air louvered door to make sure it is
physically sound, fastened securely to the furnace casing.
4. Examine the furnace casing making sure the physical
support is sound without sagging, cracks, or gaps.
5. Examine the furnace base making sure it is physically sound
without cracks, gaps, or sagging and that it has a good seal
to the casing.
6. Examine the furnace casing for obvious signs of
deterioration.
7. Examine the burner flames to make sure they are in good
adjustment. The flame should appear long and cylindrical
(Refer to Figure 2 as comparison to the actual flame.) with a
blue color. Some yellow streaks may appear especially near
the tip of the flame. (LP) Propane flame appears less blue
and has considerably more yellow streaking.
8. Examination should be done at the start of each heating
season. It is very important to examine the exterior of the
furnace every heating season with a focus on any cracks or
deterioration. The furnace should also be examined by a
qualified service agency before the start of each heating
season.
FIGURE 2: Burner Flame Drawing
FIRE OR ELECTRICAL HAZARD
Servicing heating / cooling equipment can be
hazardous due to electrical components
Only trained and qualified personnel can service or
repair heating / cooling equipment. The home owner
must never try to perform service, repair or
maintenance on this appliance.
Untrained service personnel can perform only
basic maintenance functions such as cleaning of
exterior surfaces and replacing the air filters.
Observe all precautions in the manuals and on the
attached labels when working on this appliance.

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FIGURE 3: Furnace Examination Checkpoints
SECTION II: OWNERS INFORMATION AND
SEASONAL INFORMATION
HOW YOU’RE FURNACE WORKS
Your Furnace is a very easy appliance to take for granted.
Season after season, it sits there in your home keeping you warm
and comfortable. For this reason you may never have given much
thought to the way your furnace operates. In order to get the
safest and most efficient operation from your furnace you should
understand how your furnace does its job.
This furnace may only be installed in the vertical position. Figure
3 shows a typical model in the vertical position. The furnace is
equipped with a transformer, pressure switch, integrated control
board, burner assembly, combustion air assemble, transformer,
and a blower assembly. The transformer provides 24 VAC to the
thermostat.
When you set your thermostat to provide more heat in your
home, you are starting the heating cycle of the furnace. The
heating cycle is as follows:
1. The thermostat calls for heat which places 24 VAC on the
“W” terminal on the control board.
2. 24 VAC on the “W” terminal on the control board starts the
combustion air blower motor. Operating the combustion air
blower motor will purge any remaining gases from the heat
exchanger and will send the gases out the vent.
3. Once the combustion air blower motor is running the
pressure switch will close providing there is no vent
restriction or blockage.
4. After the pressure switch closes the hot surface igniter will
be energized and will start to glow.
5. After the igniter gets hot the control will open the gas valve
and gas will start to flow of gas. The gas will ignite as it
passes by the igniter. The flame sensor will sense the
presents of a flame and send a signal back to the control
board that a flame is present. The control board will keep the
gas valve open as long as the flame sensor detects the
presents of a flame, the 24 VAC signal is present on the
control board “W” terminal and no limit switches open.
6. After ignition has been established the indoor blower motor
will be energized distributing warm air through the home.
7. When the temperature of the home has reached the setting
on the thermostat, the 24 VAC signal will be removed from
the “W” terminal on the control board. This causes the gas
valve to de-energize removing the flame from the heat
exchanger. The control board will start the indoor blower
time delay and will turn off the blower once the delay has
timed out.
8. This concludes the heating cycle until the thermostat calls
for heat again.
The furnace is equipped with the controls necessary for proper
and safe operation. The various components referred to in this
manual are identified in Figure 1.
The following list includes important facts and information
regarding the gas furnace and its inclusions.
1. Furnace is rated at 115 volts AC at 60 Hertz
2. Furnace is available in two (2) cabinet sizes.
3. All furnaces are equipped with a blower
4. This furnace is designed for downflow application only.
5. This furnace must not be operated without furnace door
installed.
GENERAL OWNER INFORMATION
1. Refer to the furnace rating plate for the furnace model
number and the operating specifications for safe operation.
2. Provide clearances for servicing ensuring service access is
allowed for the burner compartment, control box and the
blower compartment.

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3. Failure to carefully read and follow all instructions in this
manual can result in malfunction of the furnace, personal
injury, property damage and / or loss of life.
4. If the furnace is installed in a residential garage it must be
installed so that the electric heaters are located not less than
18 inches above the floor and the furnace must be located or
protected to avoid physical damage by vehicles.
5. These instructions cover minimum requirements and
conform to existing national standards and safety codes. In
some instances these instructions exceed certain local codes
and ordinances, especially those who have not kept up with
up with changing construction practices. These instructions
are to be followed and are the minimum requirement to
perform service or repairs on this appliance.
The Service Technician
The furnaces best friend is a qualified service technician. If the
unit gives any indication of improper operation, call the service
technician. The service technician is allowed to perform the
normal routine care of your furnace. He can detect potential
problems and make corrections before trouble develops.
Preventative maintenance of this type will allow the furnace to
operate with minimal concerns to the home owner and will add
years of comfort.
Warranty and Responsibilities
It is the sole responsibility of the home owner to make certain the
furnace has been properly installed and adjusted to operate
properly.
The manufacturer warrants the furnace to be free from defects in
material or workmanship for a stated time in the warranty
agreement. The manufacturer will not be responsible for any
repair costs to correct problems due to improper setup, improper
installation, improper furnace adjustments, adding parts that are
not listed for use with this furnace, improper operating
procedures by the user, ECT.
Some specific examples of service calls which will be excluded
from warranty reimbursement are:
1. Correcting faulty duct work in the home. This can be due to
not enough ducts or ducts are too small to provide proper air
flow through the furnace.
2. Correcting wiring problems in the electrical circuit to the
furnace.
3. Resetting circuit breakers or on/off switches used for
servicing.
4. Furnace problems caused by installation and operation of
any air conditioning unit, heat pump, or other air quality
devise which is not approved for use with this furnace.
5. Adjusting or calibrating the thermostat.
6. Problems caused by construction debris which has fallen
into the furnace.
7. Replacement of fuses.
8. Problems caused by dirty air filters.
9. Problems caused by restrictions in the return or supply air
flow causing low air flow.
The home owner should establish a firm understanding of these
responsibilities with the installer or service company so there no
misunderstanding at a later time.
While you are away
The furnace is equipped with safety shutoff devices which will
shut off the gas burner in case of a malfunction. For this reason it
is never practical to assume the furnace will operate unattended
for a long period of time.
If you are planning to be away from home for a long period of
time have someone check on your home everyday epically when
the outside temperatures will be below 35°F to ensure the
furnace is operating properly. This may prevent water pipes from
freezing.
When to Call For Service Assistance
Very often time can be saved if you give a service agency the
information about the furnace ahead of time. This will enable the
service agency to determine the specific components used and
possibly indentify the problem, thus arriving with the parts to fix
the problem.
SERVICE AGENCY INFORMATION
Fill in Below
COMPANY:
ADDRESS:
TELEPHONE (DAYTIME):
TELEPHONE (EMERGENCY)
SECTION III: STARTUP AND SHUTDOWN
INSTRUCTIONS
STARTUP AND SHUTDOWN INSTRUCTIONS
Read the instructions below before trying to start the furnace.
A. This appliance does not have a pilot. It is equipped with an
ignition device which automatically lights the burner. Do not
try to light the burner by hand.
B. BEFORE OPERATING; smell all around the appliance area
for gas. Be sure to smell next to the floor because some gas
is heavier than air and will settle on the floor.
C. Use only your hand to push the gas control switch to the
“ON” position. Never use tools. If the switch will not
operate by hand, don’t try to repair it. Call a qualified
service technician. Force or attempted repair may result in a
fire or explosion.
D. Do not use this appliance if any part has been under water.
Immediately call a qualified service technician to inspect the
appliance and replace any part of the control system and any
gas control which has been under water.
Operating Instructions
1. STOP! Read the safety information above and the Lighting
Instruction Label located on Burner Compartment Door.
2. Set the thermostat to the lowest setting.
3. Turn off all electric power to the appliance.
4. Remove furnace door.
5. Move gas control switch to the “OFF” position. Do not
force. See Figure 4 for switch location.
6. Wait (5) five minutes to clear out any gas. If you then smell
gas, STOP! Follow “B” in the safety information above. If
you do not smell gas, go on the next step.
7. Move gas control switch to the “ON” position. Do not force.
See Figure 4 for switch location.
If you do not follow this instruction exactly, a fire
or explosion may result causing property damage,
personnel injury, and / or loss of life.

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8. Replace the burner access panel.
9. Turn on all electrical power to the appliance.
10. Set thermostat to the desired setting. Burner will light, which
may take 30-60 seconds.
11. After three (3) trials for ignition, if the appliance will not
operate follow the instructions “TO TURN OFF THE
APPLIANCE” and call your service technician or gas
supplier.
TO TURN OFF THE APPLIANCE
1. Set the thermostat to the lowest setting.
2. Turn off all electrical power to the appliance if service is to
be preformed.
3. Remove burner access panel.
4. Move gas control switch to the “OFF” position.
5. Replace burner access panel.
The Furnace Fails to Operate Properly
If any abnormalities are observed while the furnace is operating
normally, perform the following checks:
1. Check the setting on the thermostat to make sure the
thermostat is set above the room temperature.
2. Check to see if the electrical power is turned on at the circuit
breakers at the main service circuit breaker box or check any
on/off switches that may be used for service disconnect
switches.
3. Check the 3 amp fuse on the left side of the control board to
determine if it has blown. A replacement fuse can be
purchased at your local automotive, electronics or retail store
that has an automotive department.
4. Make sure the air filters are clean, return grilles are not
obstructed, and supply air registers are open.
5. Make sure the control switch on the gas valve is in the “ON”
position. Refer to Figure 4 for control switch location.
6. Make sure the gas cock or valve shown in Figure 5 is in the
“ON” position.
If the cause of the malfunction is not obvious do not attempt to
service the furnace yourself. Call a qualified service agency to
repair the furnace.
If you do not follow these instructions exactly, a fire or explosion
may result causing property damage, personnel injury, and / or
loss of life.
Figure 4: White Rodgers 36J Gas Valve Components
Figure 5: Gas Supply Pipe Shutoff Valve Locations
NOTE: As a safety precaution all electrical power and gas
supply valves must be shut off before servicing.
SECTION IV: OWNER MAINTENANCE
Blocked Vent Shutoff System
The furnace is equipped with a combustion air pressure switch. If
the vent starts to plug up the combustion air flow will be reduced
causing the switch to open. If the pressure switch is open the user
must contact a qualified service agency
AIR FILTERS
All appliances need maintenance at the beginning of each heating
season in order to operate properly. The annual service must be
performed by a qualified service personal. The home owner is
expected to perform general cleaning of the exterior surfaces,
clean dust from the louvers in the return air door and replacement
of the air filters. Air filters must be checked every month and
replaced as needed. Figures 6 and 7 indicate the location of the
air filters in the louvered return air door.
Should overheating occur turn the gas cock or gas
valve in the gas supply line to the “OFF” position.
After the furnace has cooled off, turn the circuit
breakers on the main electrical service entrance
(Circuit Breaker Box) to the off position. Call a
qualified service personal to trouble shoot and repair
the furnace. DO NOT allow the furnace to continue to
cycle on the limit controls.
Before proceeding make sure the area is well
ventilated. Turn the thermostat “OFF”. If the blower is
running, wait until it stops automatically. Follow the
shutdown instructions located on page 6. Check all
metal parts and surfaces to be sure they have cooled to
room temperature before you begin.

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Figure 6: Return Air Filter Locations (Outside View)
Figure 7: Return Air Filter Locations (Inside View)
Every time the filters are changed, the following items should be
visually inspected.
Check combustion air and vent pipe for blockage.
Check all components to be sure they are in good condition
and that there are no obvious signs of deterioration.
Check for dirt or lint on any surfaces or on components.
Do not try to clean any of the surfaces or components,
cleaning of the furnace and its components must be done by
a qualified service professional.
If during the visual inspection of your furnace you find any of the
following conditions
Excessive amounts of dirt and lint on components.
Damaged or deteriorated components or surfaces.
Leaks or blockage in the vent pipe passages.
Water on any surface inside or outside of the furnace.
Do not operate the furnace. Call a certified dealer or service
contractor to check, and / or clean your furnace. The dealer or
service contractor can provide you with additional information or
simply answer your questions about the operation of your
furnace and why the furnace must be checked and / or cleaned.
If all components appear to be in good operating condition,
replace the front panels. Follow the startup instructions on page
6.
Replacement Air Filter Sizes
All models require two 16” x 20” x 1” high velocity air filters.
Replace the air filters with the same size and type that was
removed.
Replacing Return Grille Air Filters
Follow these easy steps to replace the filters located in the return
air grille:
1. Follow the procedure “To Turn Off the Appliance” in the
Startup and Shutdown Instructions section of these
instructions.
2. Pull back on the top of the return air grille door until it pops
out of the retainer clip.
3. Let the top of the door fall towards you then lift up slightly
pulling towards you and set the door on the floor.
4. Remove the center retaining bracket by pushing down on the
left side of the bracket then use a small straight edge screw
driver to pry it out.
5. Remove both air filters from the door. These filters are
disposable filters. DO NOT attempt to clean the filters and
reuse them.
6. Remove the filter material from the plastic wrap they come
in.
7. Place the air filters in the door.
8. Place the center retaining bracket between the two air filters.
Slide the bracket under the flange on the left side of the
door. Place a straight edge screw driver between the bracket
and the right side door flange, then, slide the bracket past the
door flange until the bracket is back into place. Use a rubber
mallet to straighten the right side door flange if necessary.
9. Lift the door up against the cabinet and align the slots in the
bottom of the door with the tabs on the divider panel.
10. Push the door forward lining up the plastic door strike in the
top cover with the hinge in the door.
11. Push the top of the door, on the left side forward until the
door strike snaps into the latch.
12. Push the top of the door, on the right side, forward until the
door strike snaps into the latch.
13. Follow the instructions to “Turn On / Start the Appliance”
in the Startup and Shutdown section of these instructions.

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SERVICE AND MAINTENANCE MANUAL
Section I SAFETY
THE HOME OWNERS AND / OR APPLIANCE USERS
MUST STOP HERE!
This section has been designed to assist a qualified service
agency in performing service and maintenance on this appliance.
The home owners and / or the appliance user must never
Attempt to perform any service or maintenance on the appliance
especially when it involves the removal or adjustment of any
parts and / or components.
The following safety rules must be followed when servicing
this furnace.
Understand and pay particular attention to the signal words
DANGER, WARNING, or CAUTION.
DANGER: indicates an imminently hazardous situation, which
if not avoided, will result in death or serious injury.
WARNING: indicates a potentially hazardous situation, which
if not avoided, could result in death or serious injury.
CAUTION: indicated a potentially hazardous situation, which if
not avoided, may result in minor or moderate injury. It is also
used to alert against unsafe practices and hazards involving
property damage.
SAFETY REQUIREMENTS
1. This gas fired furnace has a 115 volt 60 HZ electrical supply
circuit. Make sure you check each electrical circuit with a
meter to be sure the power has been disconnected.
2. Insulating materials may be combustible. The furnace must
be kept free and clear of insulating materials.
3. Follow the instructions exactly as shown in Startup and
Shutdown Section in this manual to properly Startup or
Shutdown this appliance.
4. Make sure all moving parts have come to a complete stop
before attempting to perform any work once the furnace
door has been removed. Moving parts can cause serious
injury if clothing or body parts get caught in the moving
part.
The manufacturer will not be responsible for any damage to
the appliance or for any repairs due to improper parts
changes, improper maintenance, improper furnace
adjustments or improper modifications made by the
homeowner and/or the appliance user.
The manufacturer will not be responsible for any damages
or repairs if the home owner and/or appliance user use this
section of the instructions in an attempt to perform
maintenance or repairs to the furnace. This practice is very
dangerous and may result in a fire causing property
damage, personal injury, and / or loss of life.
If the homeowner or the appliance user attempts to perform
any maintenance or repairs to this appliance, the appliance
warranty will be void and the home owner will be
responsible for all repair costs and/or damages.
Improper adjustment, service or maintenance may create a
condition where the operation of the product could cause
personal injury or property damage.
Refer to this manual for assistance or for additional
information consult a qualified contractor, installer, or
service agency.
This product must be serviced and maintained as specified
in these instructions and/or to any applicable local, state,
and national codes including, but not limited to building,
electrical
,
and mechanical codes.
FIRE OR ELECTRICAL HAZARD
Failure to follow the safety warnings exactly could result in
serious injury, death, or property damage.
A fire or electrical hazard may result causing property
dama
g
e,
p
ersonal in
j
ur
y
or loss of life.
ELECTRICAL SHOCK, FIRE HAZARD
Failure to follow the safety warnings exactly could result
in dangerous operation, serious injury, death, or
property damage.
Improper servicing could result in dangerous operation,
serious injury, death, and /or property damage.
Before servicing, disconnect all electrical power to the
furnace.
When servicing controls, label all wires prior to
disconnecting to aid in proper reconnection of wires.
Verify proper operation after servicing by turning the
thermostat above the room temperature for a brief
period of time to ensure future operation.
Placing jumper wires between the RED and WHITE
thermostat wires at the furnace in order to bypass the
thermostat and energize the heater is an extremely
dangerous practice that can result in damage to the
thermostat, dangerous operation, serious injury, death,
and/or property damage.

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Section II: FURNACE MAINTENANCE
This furnace must be cleaned and adjusted by a certified dealer
or qualified service contractor once a year or before the start of
each heating season. The following items must be cleaned and
serviced or replaced if there signs of deterioration.
1. The Roof Jack vent terminal.
2. The furnace Roof Jack combustion air intake passageways.
Should it be necessary to service the vent /air intake system,
the manufacturer recommends this service be conducted by a
qualified service agency. The operation of the appliance
requires the reassembly of the vent/combustion air intake
system to be sealed and have adequate passageways for
venting and combustion air to the appliance.
3. The burners, igniter, and flame sensor.
4. The blower wheel and the motor Also check for dirt, dust or
debris in the blower wheel and the motor.
5. The supply air duct system for excessive dust, dirt or debris
6. The return air louvered door for excessive dust, dirt or debris
7. All electrical wiring for wear and / or damage.
8. Check the air conditioning evaporator coil for dust, debris or
damage.
9. Check the evaporator coil drain pan for proper drainage to
prevent water backup into the furnace.
10. The furnace casing and all interior sheet metal panels or
dividers.
11. The vent pressure switch will open if the vent system is
blocked. The pressure switch will automatically reset when
the restriction has been removed.
12. If the pressure switch fails to close it can be replaced by
removing the hoses and removing the two (2) screws that
secure it to the vestibule panel. To install the new pressure
switch you must hold the switch to the vestibule panel and
insert the two (2) screws that were removed. Reconnect the
hoses to the correct ports.
Furnace Cleaning Procedure
NOTE: The cleaning procedure listed below must be performed
by a qualified service agency only! The home owner or
appliance user MUST STOP HERE! If you continue you do
so at your OWN RISK AND EXPENSE!
Burner Removal and Cleaning
The main burners should be removed and visually inspected for
dirt and debris accumulation every time the annual maintenance.
Follow the procedure below if cleaning is required.
1. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly shutdown
this appliance.
2. Remove the burner access door on the front of the furnace.
3. Turn off the valve in the gas supply line and loosen the
ground union joint. Refer to Figure 5.
4. Remove the gas line from the gas valve. Be sure to use a
wrench on the gas valve hub (Wrench Boss) located on the
inlet side of the gas valve to keep the gas valve from moving
when the gas line is being removed.
5. Remove the electrical wires from the terminals on the gas
valve.
6. Unplug the flame sensor and igniter wires from the insulated
spade plugs.
7. Remove the sixteen (16) screws from the burner mounting
plate and remove the burner assembly. Refer to Figure 8.
8. Lift the burner assembly up, turning slightly too clear the air
baffles and slides the burner assembly back to remove.
Empty any dirt or debris using a small soft brush and a vacuum
cleaner.
NEVER clean the burners using water. Water will cause the
burner to corrode and / or rust.
Air Filter Maintenance
The air filter should be inspected every three (3) months and
replaced as needed when they get dirty. The air filters can be
found in the front louvered door. Air filters are disposable and
cannot be cleaned. Replacement air filters are 16” x 20” x 1”.
The air filters are replaced by removing the tape on the bottom of
the louvered door and sliding them down the track. Install the
new air filters by sliding them up the track and taping the bottom
to keep them from falling out when installing the door. Refer to
Figures 6 and 7 for air filter location.
Lubrication of motor or blower is not recommended.
Figure 8: Burner Assembly
9. Re-insert the burner assembly between the air baffles and
slide forward until the burner mounting plate screw holes
line up with the holes in the burner box.
10. Secure the burner assembly to the burner box with the
screws that were removed in step 7.
11. Connect the flame sensor and igniter wire spade terminals to
the insulated spade plugs that were unplugged in step 6.
12. Reconnect the electrical wires to the terminals on the gas
valve
13. Connect the gas supply line. You should use new pipe that is
properly chamfered, reamed, and free of burrs and chips. If
you are using old pipe, be sure it is clean and free of rust,
scale, burrs, chips, and old pipe joint compound.
DO NOT OVER TORQUE the gas supply pipe into the gas
valve. If the pipe is over tightened into the gas valve it will
damage the valve.
The manufacturer recommends the hand tightening gas pipe
to the gas valve, then giving the pipe ½ turn with a wrench.
Check for leaks.
Never test for gas leaks with an open flame.
Check all gas piping connections with a commercially
available soap solution made specifically for detection of
leaks.

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Apply pipe joint compound (pipe dope) that is approved for all
gases, only to the male threads of the pipe joints. DO NOT
apply compound to the first two threads.
Be sure to use a wrench on the gas valve hub (Wrench Boss)
located on the inlet side of the gas valve to keep the gas valve
from moving when the gas line is being tightened. Do not over
tighten the gas pipe. This will cause damage to the gas valve. If
you have a torque wrench torque: 375 in-lb maximum. If you
do not have a torque wrench then tighten by hand the tighten pipe
then, turn the pipe an additional ¾ of a turn or until connection
is snug and not leaking.
14. Connect the union joint and tighten the union and turn the
manual gas valve back to the “ON” position. Refer to Figure
5 for union and gas valve locations.
15. Reinstall the burner access door on the front of the furnace.
16. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly startup
this appliance.
Figure 9: Burner Assembly, Support Plate, Retaining Screws
and Orifices
Cleaning the Heat Exchanger
1. Remove the burner assembly as described in “Burner
Removal and Cleaning” steps 1-8.
2. Remove the combustion air baffles from the burner box.
The combustion air baffles are secured to the vestibule panel
with two screws on each baffle located on the top and
bottom of the baffle.
3. Use a brush and a vacuum cleaner to clean any areas of the
inside portions of the heat exchanger that may need
cleaning.
4. Check all of the baffles for cracks and/or deterioration.
5. Use a mirror to check the baffle, inside the drum, at the top
of the heat exchanger for cracks and/or deterioration.
6. Check the heat exchanger for any visible signs of cracks or
holes.
7. Use a brush and vacuum to clean the inside portion burner
box.
8. Reinstall the combustion air baffles from the burner box.
The combustion air baffles are secured to the vestibule panel
with two screws on each baffle located on the top and
bottom of the baffle.
9. Reinstall the burner assembly as described in “Burner
Removal and Cleaning” steps 9-16.
Figure 10: Heat Exchanger Assembly w/ Dimples
Cleaning the Flue Box Assembly
1. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly shutdown
this appliance.
2. Remove the louvered filter door on the blower compartment.
3. Slide the Roof Jack combustion air and vent piping upward
as far as it will go to remove the pipes from the combustion
air and vent flanges at the top of the furnace.
4. Remove the four screws that secure the blend air adapter to
the top cover. (If a blend air system is being used)
5. Remove the eleven (11) screws from the furnace top cover.
Refer to Figure 11.
CARBON MONOXIDE HAZARD
If the gaskets on the combustion air blower assembly or the
flue box cover have been damaged, but have not been
replace there is a potential of these parts to develop leaks in
the combustion system. These leaks will cause incomplete
combustion to occur causing high levels of carbon
monoxide to leak into the living space.
Under no circumstances should this equipment be operated
if these gaskets have been damaged.
TURN THE FURNACE OFF UNTIL THE GASKETS
HAVE BEEN REPLACED!!

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Figure 11: Top Cover Screws and Combustion Air Pan
Screws
6. Remove the three ¼-20 nuts next to the flue collar.
7. Remove the two 3/16-16 Phillips screws from the flange at
the top of the four (4) inch combustion air pipe located
inside the blower compartment. Refer to Figure 11.
Figure 12: Four (4) Inch Combustion Air Tube Flange
8. Remove the three screws from the combustion pan cover.
Refer to Figure 12.
9. Remove the top cover. Be very careful not to damage the
insulation and the gaskets. If the insulation or the gaskets get
damaged they must be replaced.
10. Remove the sixteen (16) screws from the flue box cover. Do
not mix these screws with the other screws as these are
stainless because of the heat. Refer to Figure 13 for screw
locations.
Figure 13: Flue Box Cover Screws
11. Remove the flue box cover. Be very careful not to damage
the gasket on the flange. If the gasket get damaged it must be
replaced.
12. Now you can take a brush and vacuum and clean the tubes
and the flue box area. Remember, the debris removed from
the wall of the tubes by the brush will fall into the base of
the heat exchanger. You must vacuum the base to remove
the debris when you have finished brushing the tubes.
13. Place the flue box cover back on top of the flue box base and
secure with the stainless screws that were removed in step 9.
Make sure the gasket is not damaged because you must have
a good seal for the furnace to operate properly.
14. Place the top cover back on top of the furnace. Make sure
the bolt holes in the combustion air pan line up with the ¼-
20 bolts next to the flue collar. Make sure the gasket is
between the combustion air pan and the flue box is not
damaged. If the gasket is damaged, replace it. You must
have a good seal between the combustion air pan and the
flue box to prevent leaking.
15. Install the three (3) - ¼-20 nuts on the three (3) bolt and
tighten until secure.
16. Install the eleven (11) screws back in the top cover and
tighten until they are secure. Do not over tighten as they will
strip.
17. Place the blend air bracket over the four inch hole and align
the screw holes, then install the screws to secure it to the top
cover. (Bypass this step if you do not have a blend air
system).
18. Place the louvered filter door back on the blower
compartment.
19. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly startup
this appliance.
Figure 14: Flue Box Assembly
Cleaning the Combustion Air Assembly
The combustion air assembly should be removed and visually
inspected for dirt and debris accumulation every time you find
excessive dirt and debris in the burner box while performing the
annual maintenance. Follow the procedure below if cleaning is
required.
1. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly shutdown
this appliance.
2. Remove the louvered filter door on the front of the furnace.
3. Remove the burner compartment door on the front of the
furnace.
4. Turn off the valve in the gas supply line and loosen the
ground union joint. Refer to Figure 5.
5. Remove the gas line from the gas valve. Be sure to use a
wrench on the gas valve hub (Wrench Boss) located on the
inlet side of the gas valve to keep the gas valve from moving
when the gas line is being removed.
6. Remove the electrical wires from the terminals on the gas
valve.

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7. Unplug the flame sensor and igniter wires from the insulated
spade plugs.
8. Remove the ten (10) screws from the burner mounting plate
and remove the burner assembly. Refer to Figure 8.
9. Lift the burner assembly up, turning slightly too clear the air
baffles and slides the burner assembly back to remove.
10. Remove the ¼” tube from the top right side of the burner
box.
11. Remove the four (4) screws that secure the combustion air
baffles to the burner box / vestibule panel. Refer to Figure
16.
12. Remove the four (4) remaining screws that secure the burner
box to the vestibule panel. Be careful not to damage the
gasket on the back side of the burner box. If the gasket is
damaged, replace it. There must be a good seal between the
burner box and the vestibule panel for the furnace to operate
properly. Refer to Figure 16.
13. Remove the two (2) Phillips screws the secure the bottom of
the combustion air assembly to the 4” pipe.
14. Grab the burner box and twist slightly while pulling down to
remove the four inch (4”) pipe from the combustion air
housing. Refer to Figure 16.
15. Unplug the male and female insulated spade terminals that
go to the combustion air assembly.
16. Remove the two (2) screws in the top of the combustion air
housing, then, remove the assembly from the upper four inch
(4”) pipe. Refer to Figure 16.
17. Use a soft bristle brush and a vacuum to clean the dirt and
debris from the housing, motor and prop fans. Be careful not
to damage the plastic fans. Use the vacuum when brushing
the pipe and fan in a manor to prevent the dirt or debris to
entering the motor windings. Dirt or debris will cause the
motor to run hotter reducing motor life.
18. Place the round black gasket on the four inch (4”) upper pipe
so that the pipe sits inside the grove in the gasket, then, slide
the combustion air housing into the gasket and secure the
housing to the four inch (4”) pipe with the two (2) screws.
Make sure the gasket is properly inserted into the pipe so
there is a good seal at the pipe and around the combustion
air housing. Refer to Figure 16.
19. Place the round black gasket on the four inch (4”) lower pipe
so that the pipe sits inside the grove in the gasket, then, slide
the combustion air housing into the gasket and secure the
housing to the four inch (4”) pipe with the two (2) screws.
Make sure the gasket is properly inserted into the pipe so
there is a good seal at the pipe and around the combustion
air housing. Refer to Figure 15.
20. Place the gasket on the back side of the burner box so it is in
between the burner box and the vestibule panel. If the gasket
is damaged, replace it. There must be a good seal between
the burner box and the vestibule panel for the furnace to
operate properly. Install the four (4) screws that were
removed in step 11 and tighten until secure.
21. Place the combustion air baffles into the burner box and use
the four (4) screws that were removed in step 10 to secure
the baffles to the burner box.
22. Connect the ¼” tube to the nipple located on the top right
side of the burner box. Refer to Figure 16.
23. Install the burner assembly and secure the assembly to the
burner box with the ten (10) screws that were removed in
step 8.
24. Connect the two (2) ¼” male and female spade terminals for
the igniter. The igniter has the two (2) white wires with the
high temperature insulation.
25. Connect the ¼” male and female spade terminal for the
flame sensor. The flame sensor has one (1) yellow wire.
26. Connect the brown wires to the electrical spade terminals on
the gas valve.
27. Connect the gas supply line. You should use new pipe that is
properly chamfered, reamed, and free of burrs and chips. If
you are using old pipe, be sure it is clean and free of rust,
scale, burrs, chips, and old pipe joint compound. Apply pipe
joint compound (pipe dope) that is approved for all gases,
only to the male threads of the pipe joints. DO NOT
apply compound to the first two threads.
Be sure to use a wrench on the gas valve hub (Wrench Boss)
located on the inlet side of the gas valve to keep the gas
valve from moving when the gas line is being tightened.
Do not over tighten the gas pipe. This will cause damage to
the gas valve. If you have a torque wrench torque: 375 in-lb
maximum. If you do not have a torque wrench then tighten
by hand the tighten pipe then, turn the pipe an additional ¾
of a turn or until connection is snug and not leaking.
28. Connect the union joint and tighten the union and turn the
manual gas valve back to the “ON” position. Refer to Figure
5. You should check the entire gas supply line for leaks
again to be sure nothing is leaking.
29. Place the lower burner door back on the furnace.
30. Place the louvered filter door back on the furnace.
31. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly startup
this appliance.
Figure 15: Combustion Air Assembly
Cleaning the Indoor Fan Assembly
1. Follow the instructions exactly as shown in Startup and
Shutdown Section in this manual to properly shutdown this
appliance.
2. Remove the louvered blower compartment access door
located on the front of the furnace.
3. Remove the louvered burner compartment access door
located on the front of the furnace.

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4. Unplug the blower motor wire harness six (9) pin plug
located on the right side of the control box.
5. Remove the two screws on the right side of the blower
mounting bracket.
6. Remove the two (2) screws on the left side of the blower
mounting bracket.
7. Lift the blower upward while moving to the left, then, pull
the blower back to remove.
8. Use a vacuum cleaner and a small brush to remove any dirt
and debris from the blower compartment.
9. Check in the area below the blower compartment where the
heater exchanger tubes are located and remove any dust, dirt
or debris from around the heater elements. Be careful not to
damage the heater exchangers with the vacuum hose or the
brush. Make sure you place a piece of cardboard on top
of the “A” coil to collect the dirt and debris so it does not
go into the coil.
10. Check the blower wheel for dust and debris. Use the brush
and the vacuum cleaner to remove any dust or debris from
the wheel. Be careful not the move or accidentally remove
the blower wheel balance weight located on the wheel fins.
If it is moved or removed it will cause the blower wheel to
vibrate. If the wheel is vibrating, you must replace it.
11. Check the blower motor for dust and debris. Be sure to clean
the openings on the motor housing as these openings are
used to cool the motor. If dust, dirt or debris has not been
removed it from these openings will cause the motor to run
hotter than normal and will shorten the life of the motor.
12. Reinstall the blower assembly and secure the assembly using
the screw that was removed in steps 3 and 4.
13. Connect the blower motor wire harness (9) pin Male plug to
the (9) pin female plug located on the right side of the
control box.
14. Reinstall the burner compartment access door on the front of
the furnace.
15. Reinstall the louvered blower compartment access door on
the front of the furnace.
16. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly startup
this appliance.
Figure 16: Blower Assembly
Figure 17: Component Location

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Section III: FURNACE OPERATION
FURNACE CONTROLS
This section discusses the furnace controls and how they operate.
Refer to Figure 18 for component locations.
1. The Limit Controls – The furnace has a limit control
located on the vestibule panel to sense overheating of the
heat exchangers and open if the temperature gets above the
set point of the limit control.
2. The Rollout Limit Controls – The burner assembly has two
(2) limit controls to shutdown the burner operation if either
of the limits open.
3. The Furnace Integrated Control – The integrated Hot
Surface Ignition control combines all control functions
needed for an induced draft mobile home furnace into a
single printed circuit board package.
The control provides outputs for a 2 speed taps for the
indoor blower motor speed tap leads, single speed inducer
motor, main gas valve, and hot surface igniter element. The
control receives inputs from the thermostat (W and G),
pressure switch, high temperature limit switches, and senses
flame
4. Pressure Switches – The pressure switches sense the
pressure in the induced draft housing and closes the contacts
when the negative pressure is above the set point.
5. Induced Draft Assembly – This consists of a motor, blower
wheel and scroll. This assembly draws the combustion air
and the by-products of combustion through the heat
exchanger tubes and pushes them up the vent.
6. 3 Amp Fuse – This is an automotive type fuse that is used
for over-current protection of the 24 VAC circuit.
7. Transformer – The transformer is used to step down
voltage from 240 VAC to 24 VAC. The transformer
provides the required 24 VAC for the system control circuit
8. Blower Relay – This relay id connected to the “HEAT”
terminal on the control board. This relay will keep the
blower operating if the gas valve gets stuck open.
SECTION IV: SEQUENCE OF OPERATION
Normal Heating Mode Sequence
The thermostat calls for heat by energizing the "W" terminal.
The control checks to see the pressure switch is open. If the
pressure switch is closed when the call for heat occurs, the
control will lockout and begin to flash "3" on the Status LED
after 60 seconds.
The control energizes the induced draft motor and waits for the
pressure switch to close. If the pressure switch does not close
within 60 seconds of the inducer energizing, the control will
lockout, de-energize the inducer, and begin to flash "2" on the
Status LED.
The control runs the inducer for a 25 second pre-purge time,
during which the pressure switch must remain closed.
The control energizes the HSI output for 25 seconds. The inducer
remains energized, and the pressure switch must remain closed.
The control energizes the main gas valve for 5 seconds. The
inducer and igniter outputs remain energized.
The control de-energizes the hot surface igniter. The gas valve
and inducer outputs remain energized. If flame is present 2
seconds after the igniter de-energizes, the control goes to blower
on delay. If flame is not present, the control de-energizes the gas
valve and proceeds with the ignition re-try.
If flame is present, the control energizes the blower on HEAT
speed after the selected blower on delay following flame being
proven. The gas valve and inducer outputs remain energized.
The Control inputs are continuously monitored to ensure limit
and pressure switches are closed, flame is established, and the
thermostat call for heat remains.
When the thermostat demand for heat is satisfied, the control de-
energizes the gas valve. The inducer output remains on for a 15
second post-purge period.
The indoor blower motor is de-energized after the selected
blower off delay. Blower off delay timing begins when the
thermostat is satisfied.
Interrupted Thermostat
If the thermostat demand for heat is removed before the flame
recognition period, the control will run the inducer for the post
purge period and de-energize all outputs.
If the thermostat demand for heat is removed after the flame
recognition period (successful ignition), the induced draft motor
will run through a post purge and the indoor blower motor will
run on heat speed for the selected delay off time.
Ignition Re-try
If flame is not established on the first trial for ignition period, the
gas valve is de-energized and the inducer remains energized for
an inter-purge period of 25 seconds. The igniter is then re-
energized for a warm up period, and the control initiates another
trial for ignition. This sequence repeats for up to 4 trials for
ignition.
If flame is not established on the fourth trial for ignition (initial
try + 3 re-tries), the control de-energizes the gas valve, flashes
"1" on the Status LED, and lockouts out heat operation for 1
hour.
Ignition Re-cycle
Flame must not be sensed for 2 seconds before the control
responds to a loss of flame. If flame is established and
maintained during the trial for ignition period and then flame is
lost, the gas valve is de-energized within 0.8 seconds, the
induced draft motor continues to run, and the control begins
timing the 25 second inter-purge delay. The indoor blower motor
will be energized and/or remain energized on heat speed for the
selected delay off time.
When the inter-purge delay is over, the igniter is re-energized,
and the control initiates another igniter warm-up and ignition
activation period. The control will re-cycle up to 6 flame losses
(5 re-cycles) within a single call for heat before going to lockout.
Continuous Fan
Cooling / heating thermostats have a fan switch that has an “ON”
and: AUTO” position. In the “ON” position the thermostat calls
for continuous fan (G) without a call for heat, the indoor fan is
energized on the Constant Circulation speed after a 0.25 second
delay.
When the thermostat removes the call for fan ("G"), the control
de-energizes the cooling speed fan after a fan off delay period of
20 seconds.
If a call for heat (W) occurs during the blower constant
circulation speed, the blower will change to the heating speed.
When the call for heat has been satisfied the blower motor will
switch back to the Constant Circulation Speed.
If a call for cooling (Y) occurs during the blower constant
circulation speed, the blower will change to the cooling speed.

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When the call for cooling has been satisfied the blower motor
will switch back to the Constant Circulation Speed.
Intermittent Blower - Cooling
Cooling - the thermostat calls for cooling and the indoor fan is
off, the thermostat sends a 24 VAC signal to the (Y) terminal.
The indoor fan is energized on the COOL speed after a 0.25
second delay.
When the thermostat removes the 24 VAC signal from the ("Y")
terminal the control de-energizes the cooling speed fan after a fan
off delay period of 20 seconds.
Intermittent Blower - Heating
Heating - the thermostat calls for heating and the indoor fan is
off, the thermostat sends a 24 VAC signal to the (W) terminal.
The indoor fan is energized on the HEAT speed after a 0.25
second delay.
When the thermostat removes the 24 VAC signal from the ("W")
terminal the control de-energizes the heating speed fan after a fan
off delay period of 20 seconds.
VERY IMPORTANT NOTE: The blower speed taps on control
board are not used. They are powered at 120 VAC. The blower
motor speed tap wires are 24 VAC and are connected to a relay
with a 120 vac coil that is connected to the HEAT and
NEUTRAL terminals on the control board. If the blower motor
speed tap wires are connected directly to the HEAT and COOL
speed tap terminals on the control board you will fry the motor.
Limit Switch Operation
Any time the limit switch opens, the gas valve and igniter will be
de-energized, the indoor blower motor will run on heat speed, the
induced draft motor will run continuously, and the Status LED
will flash a fault code of “4”.
If the switch re-closes after being open for less than 6 minutes,
the induced draft motor will run through a post-purge delay, and
the indoor blower will run through the selected blower off delay.
The control will then attempt another ignition cycle, beginning
with the pressure switch check.
If the limit switch opens 3 times during the same call for heat,
and closes in less than 6 minutes each time, the control will enter
a 1 hour lockout period, and, continuing to flash "4" on the Status
LED during the lockout period.
Limit Switch Lockout
If the limit switch opens, and remains open for more than 6
minutes, the control will enter a fan failure mode routine. The
inducer and indoor blower will be de-energized after the limit
switch has been open for 6 minutes, and the control will be
locked out, until the thermostat is reset, or power is removed.
When the control has entered this lockout mode, after the limit
switch has reclosed, all outputs remain off for 15 minutes.
Following the 21 minute delay, the control attempts an ignition
trial. After flame is established, the control will operate for 25
seconds, and then de-energize the gas valve and the inducer after
a post purge period. All outputs will then remain off for another
15 minute period. The sequence is then continually repeated,
with the LED flashing a fault code of “4”, until the lockout
condition is reset.
Pressure Switch
If the pressure switch opens for more than 2 seconds after flame
has been established, the control shall de-energize the gas valve,
run through a normal 15 second post-purge and selected heat
blower off delay. When the blower off delay is complete, the
control shall start an ignition sequence if the thermostat is still
calling for heat.
The control shall ignore pressure switch openings of less than 2
seconds (the gas valve will momentarily de-energize while the
pressure switch is open, this may cause a loss of flame and the
control will respond to the lost flame).
If the pressure switch opens for more than 2 seconds during a
pre-purge or inter-purge, the control shall wait for the pressure
switch to re-close. The purge time re-starts when the pressure
switch closes. If the pressure switch remains open for 60
seconds, the control will lockout, de-energize the inducer, and
begin to flash "2" on the Status LED.
Undesired Flame
If flame is sensed longer than 4 seconds while the gas valve is
de-energized, the control shall energize the induced draft motor
and indoor blower motor on heat speed, keep the other outputs
off, and flash an LED fault code of “5”.
When flame is no longer sensed, the induced draft motor will run
through post-purge and the indoor heat speed blower motor will
run through the selected blower off delay time.
The control will not be locked out, and continue with normal
operation following the blower off delay.
Lockout
The control shall not initiate an ignition attempt or continuous
fan operation while in lockout. The control will still respond to
an open limit and undesired flame. Lockout shall automatically
reset after 1 hour. Lockout may be manually reset by removing
power from the control for more than 1 seconds or removing the
thermostat call for heat for more than 2 seconds.
If a gas valve hardware fault, a flame sense hardware fault, or the
limit switch open for more than 5 minutes has occurred, the
control will be in a hard lockout condition. To reset the lockout,
power must be removed from the control for more than 1 second,
or the thermostat call must be removed for more than 2 seconds.
Furnace Control Diagnostics
Control Status Indicator
A Green LED labeled “STATUS” is provided to indicate system
faults.
Steady ON - Control Ok
Steady OFF - Control fault or no power
1 flash - Lockout due to failed ignition
2 flashes - Pressure switch fault, pressure switch stuck open
3 flashes - Pressure switch fault, pressure switch stuck closed
4 flashes - Limit switch is open / limit switch fault or five limit
cycles during single call for heat, or limit open for more than 5
minutes)
5 flashes - Flame sense or gas valve fault
Rapid flash - L1/neutral reversed or voltage not present on L1

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Figure 18: Integrated Control Board
Section V: TROUBLE SHOOTING
The following checks should be made before trouble shooting the
furnace controls for a no heat issue. If the integrated control
board led is not lit check the following
1. Check the all of the circuit breakers. Make sure they are
turned to the “ON” position and have not tripped.
2. Check all fuses, especially the 3 amp fuse on the left side of
the integrated control. If the fuse is blown, check the wiring
with an OHM meter for a short to ground. Repair the short,
and then replace the fuse.
3. Check any switches that are external to the furnace to make
sure they are turned on.
4. Make sure all wiring connections especially on any of the
components are ensure and are securely fastened.
5. Check electrical power on both the 115 VAC terminals and
the 24 VAC terminals. If both have power, check the
thermostat terminals for 24 VAC. If 24 VAC is present on
“W” and “COM”, check the ground connection. If the
ground connection is good but integrated control will not
operate then replace the integrated control.
6. Check all gas line shutoff valves. Make sure the valves are
in the “ON” position.
7. If the furnace is operating but not correctly, review the
sequence of operation and observe the furnace operation to
determine what component is malfunctioning. If this does
not help then check the Trouble Shooting Guide in the back
of this manual.
Replacing the Blower
1. Follow the instructions exactly as shown in Startup and
Shutdown Section in this manual to properly shutdown this
appliance.
2. Remove the louvered blower compartment access door
located on the front of the furnace.
3. Remove the louvered burner compartment access door
located on the front of the furnace.
4. Unplug the blower motor wire harness six (9) pin plug
located on the right side of the control box.
5. Remove the two screws on the right side of the blower
mounting bracket.
6. Remove the two (2) screws on the left side of the blower
mounting bracket.
7. Lift the blower upward while moving to the left, then, pull
the blower back to remove.
8. Remove the blower motor and replace with a new motor.
9. Reinstall the blower assembly and secure the assembly using
the screw that was removed in steps 3 and 4.
10. Connect the blower motor wire harness (9) male pin plug to
the (9) pin female plug located on the top right side of the
control box.
11. Reinstall the burner compartment access door on the front of
the furnace.
12. Reinstall the louvered blower compartment access door on
the front of the furnace.
13. Follow the instructions exactly as shown in the “Startup and
Shutdown Instructions” in this manual to properly startup
this appliance.
14. Set the thermostat to the desired temperature.
For personnel safety be sure to turn the electrical
power “OFF” at the main entrance (Circuit Breaker
Box) and at the furnace before attempting any service
or maintenance operations. Home owners must never
attempt to perform any maintenance on the furnace or
do anything that required opening or removing any
furnace doors or panels.
To avoid personnel injury or property damage, make
certain that the motor leads cannot come into contact
with non-insulated metal components of the unit.
To avoid personal injury take precautions not to come
into contact with non-insulated electrical components.
Avoid wearing loose clothing or any items that can
come in contact with moving parts such as the blower
wheel. This can cause serious personal injury.
CONTROL BOARD FLAME SENSE
Normal flame sense current is approximately 2.8 micro amps DC.
Minimum flame sense current threshold is 0.5 micro amps DC.

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Figure 19: White Rodgers 36J Gas Valve
Table 1: Inlet Gas Line Pressure
Table 2: Manifold Gas Pressure
SECTION VI: BLOWER PERFORMANCE
Table 3: Blower Performance -10 x 8 Blower.
SECTION VII: ACCESSORY AND REPLACEMENT PARTS LISTS
Table 4: Accessory Parts List
Parts are available by contacting Mortex Products, Inc at the address listed on page 1 of this Manual.
Configuration SPDTap0.10.20.30.40.5
1 635 463 194
2 754 671 549 400 204
3 964 901 814 734 630
4 1134 1078 1007 943 857
5 1286 1217 1157 1094 1026
CFM‐NOCOIL
G18DxxxAH3BA‐10x8WHEEL1/3HP5SPDCONSTANTTORQUEMOTOR
Configuration SPDTap 0.1 0.2 0.3 0.4 0.5
1 635 463 194
2 754 671 549 400 204
3 964 901 814 734 630
4 1134 1078 1007 943 857
5 1286 1217 1157 1094 1026
G18DxxxCA3BA‐10x8WHEEL1/3HP5SPDCONSTANTTORQUEMOTOR
CFM‐NOCOIL
Configuration SPDTap0.10.20.30.40.5
1 694 517 137
2 1114 986 839 642 289
3 1405 1308 1201 1087 949
4 1697 1599 1486 1378 1255
5 1829 1739 1648 1552 1467
G18DxxxCA4BA‐10x8WHEEL3/4HP5SPDCONSTANTTORQUEMOTOR
CFM‐ NOCOIL
Part No Description Notes
90-RJF1729-AL Body, Roof Jack - FLAT Height - 29"
90-RJF2551-AL Body, Roof Jack - FLAT Height - 51"
90-RJS1729-AL Body, Roof Jack - Slope 3/12 Height - 29"
90-RJS2551-AL Body, Roof Jack - Slope 3/12 Height - 51"
90-RJS3868-AL Body, Roof Jack - Slope 3/12 Height - 68"
90-RJS6399-AL Body, Roof Jack - Slope 3/12 Height - 99"
90-RJCRWN-AL Crown - Roof Jack Use w/ Roof Jack Body
90-TRN-RNG Ceiling Trim Ting - Roof Jack Trim out inside RJ pipe
RJTRC Kit - Transit Roof Jack Used for transport. Remove on site
90-OUTXT160AL Roof Jack Outdoor Extension - 16" Extends Roof Jack Crown 16"
90-ICXST10-AL Roof Jack Indoor Extension - 10" Extends Indoor Roof Jack 10"
90-RJS56 6/12 Pitch Transition Kit Used to adapt to 3/12 pitch roof
90-DCU-01 Duct Connector Assembly Trasition duct for 2" to 4" Floor Depth
90-DCU-02 Duct Connector Assembly Trasition duct for 6" to 8" Floor Depth
90-DCU-03 Duct Connector Assembly Trasition duct for 10" to 12" Floor Depth
90-DCU-04 BMH/E30 Duct Transition Transition for E30 Furnact to BMH Duct Connector
90-DCU-05 Combustible Floor Base Insulated Floor Base
90-DCU-06 Floor Base Floor Base
90-CABEXT4 White Top Cabinet Extender Plate Fill Alcove 76" Top Opening
90-CALEXT-4 White Top Cabinet Extender Plate Fill Alcove Top Opening

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Figure 20: Replacement Parts Item Identification

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Table 5: Replacement Parts List
ITEMNO. USED ON FURNACEMODEL PART NO. QTY DESCRIPTION
1 All R68DD0010 1 Pres s u re Swit ch, -0.20 N.O.
All 71CA0008 2 ft. Silicon Tu bing - 9"
All 71CA0009 Silicon Tubing - 13"
3 All 68CA0005 1 Limit Switch, Manual, Upper-180F
4 All R86GF0050 1 Combustion Air Blower Assembly (No Orifices)
5 All R68GF0014 1 UTEC Integrated Control Board, HSI
6All R68GF0012 1 WR 36J Gas Valve for HSI Electric Ignition
7 All 86GF0073 1 Gas Manifold Pipe w/ Mounting Bracket
8 All 87BBG006 1 Gas Valve Support Bracket
9All 86GF0106 1 Heat Exchanger & Gaskets
10 A ll 87TEU001 1 Stainles s Perfo rat ed Diffu s er Baffle
11 All 77GC0001 1` Stainless Perforated Diffuser Baffle Gasket
12 All R68GF0004 1 Flame Sens or
13 All 68DD0009 1 Sys tem Switch - SPST
14 All R68GF0002 1 Trans former (115V-24V, 40VA )
15 All 68CA0004 1 Limit Switch - Open 140 F - Clos e 110 F
16 All R86GF0054 1 Burner Ass embly
17 All R68GF0005 1 Hot Surface Igniter
18 All 76AA0012 2 Filter (16" X 20" X 1") Pleated
19 All R86GF0082 1 Louvered Door - Upper
20 All 86GF0118 1 Control Box Ass embly
All 86GF0112 1 Door Panel - Lower 56" Tall Furnace
All 86GF0115 1 Door Panel - Lower 77.5" Tall Furnace
All 65BV0021 1 Motor - 1/3 HP Genteq
All 65BV0021B 1 Motor - 1/3 HP Nidec
All 65BV0021C 1 Motor - 1/3 HP Broad Ocean
All 65BV0023 1 Motor - 3/4 HP Genteq
All 65BV0023B 1 Motor - 3/4 HP Nidec
All 65BV0023C 1 Motor - 3/4 HP Broad Ocean
All 66AB0009 1 Motor Mount Band
All 66AB0066 3 Motor Mount Arms with Grometts
All 66CA0002 1 Screw 1/4-20 x 1 1/4 hex bolt
All 66CC0006 1 5/16" Flat Washer
24 All 69AB0001 1 Blower Wheel - 10 x 8
25 All 66AB0031 4 Door Latch, Set
60,000 Input (Natural Gas) 72AG-144 1 Main Burner Orifice - #27
70,000 Input (Natural Gas) 72AG-157 1 Main Burner Orifice - #22
77,000 Input (Natural Gas) 72AG-166 1 Main Burner Orifice - #19
90,000 Input (Natural Gas) 72AG-173 1 Main Burner Orifice - #17
60,000 Input (Propane) 72AG-086 1 Main Burner Orifice - #44
70,000 Input (Propane) 72AG-0935 1 Main Burner Orifice - #42
77,000 Input (Propane) 72AG-096 1 Main Burner Orifice - #41
90,000 Input (Propane) 72AG-104 1 Main Burner Orifice - #37
27 All 87AF0010 1 Burner Mount Plate
28 All 73XA0017 1 9 Pin W ire Harnes s
29 All 87TE1001 1 Top Heat Exchanger Restriction Baffle
G18D Gas Furnace Parts List
26
21
2
22
23