Carrier 48MA Guide

User’s Information Manual
NOTE TO INSTALLER
This manual should be left with the equipment owner.
FOR YOUR SAFETY
Do not store or use gasoline or other flam-
mable vapors and liquids in the vicinity of this
or any other appliance.
Improperinstallation,adjustment,alteration,serv-
ice or maintenance can cause injury or prop-
ertydamage. Refer to this manual.For assistance
or additional information consult a qualified in-
staller, service agency, or the gas supplier.
FOR YOUR SAFETY
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.
• 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.
Before performing recommended maintenance, be sure
main power switch to unit is turned off. Electrical shock
could cause personal injury.
Your combination heating/cooling unit is equipped with
an automatic intermittent pilot and induced draft power com-
bustion blower.
Pilot will light automatically. Do not attempt to light by
hand; personal injury may result.
TO LIGHT UNIT
1. Do not turn off the electrical power to unit without
first turning off the gas supply.
2. Before attempting to start the gas heating section, fa-
miliarize yourself with all the procedures that must
be followed.
3. Never attempt to manually light the pilot on unit with
a match, lighter, or any other flame. If the electric
sparking device fails to light the pilot, refer to the
shutdown procedures, then call your dealer as soon
as possible.
If you do not follow these instructions exactly, a fire
or explosion may result, causing property damage, in-
jury, or loss of life.
See Fig. 1 for location of gas valves. Refer to Fig. 2 while
proceeding with the following steps.
Step 1 — Set room thermostat to the lowest temperature
setting and set SYSTEM switch to HEAT.
Step 2 — Close the external manual gas valve.
Step 3 — Turn off the electrical supply to the unit.
Step 4 — Remove the burner compartment access panel.
Step 5 — Turn the control dial on the internal gas valve
clockwise to the OFF position and wait 5 minutes.
Step 6 — Turn control dial on internal gas valve clock-
wise to ON position.
Step 7 — Replace the burner compartment access panel.
Step 8 — Turn on the electrical supply to unit.
Step 9 — Open the external gas valve.
Step 10 — Set room thermostat selector slightly above
room temperature to start unit. The induced-draft combus-
tion air fan will start. Pilot lights within 30 seconds. Main
gas valves will open and main burners should ignite within
2 minutes from the pilot light ignition. Indoor blowers will
start within a few minutes of main ignition. On 48MA units,
if burners do not light within 2 minutes, the ignition control
will lock out. Begin again at Step 1. If burners still do not
light, contact your dealer for service.
Step 11 — Set the temperature selector on room thermo-
stat to desired setting.
48 Series
Gas Heating/Electric Cooling Units
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 1
Tab 1a 1c PC 111 Catalog No. 564-920 Printed in U.S.A. Form 48-13SO Pg 1 3-98 Replaces: 48-12SO

If the pilot fails to light, the main burners fail to light,
or the blower fails to come on, shut down gas heating
section and call your dealer for service. Failure to
follow these requirements could result in serious
personal injury.
TO SHUT UNIT OFF
Do not turn off the electrical power to unit without first
turning off the gas supply.
Failure to follow these procedures can result in
serious fire or personal injury.
See Fig. 1 for location of gas valve. Refer to Fig. 3 while
proceeding with the following steps.
Step 1 — Set room thermostat to lowest temperature set-
ting and set SYSTEM switch to OFF.
Step 2 — Close the external manual gas valve.
Step 3 — Turn off the electrical power supply to the unit.
Step 4 — Remove the burner compartment access panel.
Step 5 — Turn the control dial on the internal gas valve
counterclockwise to the OFF position.
Step 6 — Replace the burner compartment access panel.
Step 7 — If unit is being shut down because of a mal-
function, call your dealer as soon as possible.
If unit is being shut down because the heating season has
ended, restore electrical power to the unit to ensure opera-
tion of the cooling system during the cooling season.
Should overheating occur, or the gas supply fail to shut
off, shut off the manual gas valve to the furnace before shut-
ting off the electrical supply.
Do not use this furnace if any part has been under water.
Immediately call a qualified service technician to inspect the
furnace and to replace any part of the control system and
any gas control which has been under water.
MAIN MANUAL GAS
SUPPLY VALVES HEAT EXCHANGER
SECTION
MAIN REDUNDANT
GAS VALVES (ZONES)
PILOT BURNERSFORCED DRAFT
FAN MOTOR
48MA
NOTE: High heat consists of sections 1 and 2. Low heat consists of
section 1 only. 48DJ,DK,FJ,FK,JJ,JK034-048
NOTE: High heat consists of sections 1-3. Low heat consists of sec-
tions 1 and 2 only.
48DJ,DK,FJ,FK,JJ,JK054-074
Fig. 1 — Heat Section Details
2

STEP 1 STEP 2 STEP 3
STEP 4 STEP 5
STEP 6 STEP 7
STEP 8 STEP 9 STEP 10
Fig.2—ToLight Unit
3

STEP 1 STEP 2 STEP 3
STEP 4
STEP 5
STEP 6 STEP 7
Fig.3—ToShut Unit Off
4

MAINTAINING YOUR UNIT
All maintenance should be handled by skilled, experi-
enced personnel. Your dealer can help you establish a stand-
ard procedure.
For your safety, keep the furnace area clear and free of
combustible materials, gasoline and other flammable liquids
and vapors.
To assure proper functioning of the unit, flow of combus-
tion and ventilating air must not be obstructed from reaching
the furnace. Clearance of at least 4 ft on all sides is required.
ROUTINE MAINTENANCEAND CARE FOR THE
EQUIPMENT OWNER
Before proceeding with those things you might want to
maintain yourself, please carefully consider the following:
1. TURN OFF GAS SUPPLY AND ELECTRICAL
POWER TO YOUR UNIT BEFORE SERVICING
OR PERFORMING MAINTENANCE.
2. Do not turn off electrical power to this unit without
first turning off the gas supply.
3. When removing access doors or performing main-
tenance functions inside your unit, be aware of sharp
sheet metal parts and screws. Although special care
has been taken to reduce shap edges to a minimum,
be extremely careful when handling parts or reach-
ing into the unit.
Air Filter(s) — Air filter(s) should be checked at least
every 3 or 4 weeks and changed or cleaned whenever they
become dirty.Table 1 indicates the correct filter size for your
unit. Remove the filter access panel to replace or inspect the
filters. All units have filter tracks in which the filters slide.
Remove the filters by pulling outward from the track. See
Fig. 4 for filter access panel location. Note the direction of
flow arrows on the filter frame.
For horizontal supply/return units, the size, location and
number of air filters varies from Table 1. If you have diffi-
culty in locating your air filter in the return-air duct system,
or if you have questions concerning proper filter mainte-
nance, contact your dealer for instructions.
When replacing your unit filters, always use the same size
and type of filter that was originally supplied by the
installer.
Units with outdoor air capability have a cleanable filter
for the outdoor air. This filter should be checked annually
and cleaned as necessary. Remove by removing screws in
outdoor air filter retainer and sliding filters out of the unit.
Never operate your unit without filters in place. Failure
to heed this warning may result in damage to the blower
motor and/or compressor. An accumulation of dust and
lint on internal parts of your unit can cause loss of ef-
ficiency and, in some cases, fire.
Table 1 — Indoor Air Filter Data*
UNIT† TYPE QTY...SIZE (in.)
48MA
Disposable
Fiberglass
12...20 x 25 x 2
48DJ,DK,FJ,FK,JJ,JK034-048 12...20 x 25 x 2
4...16 x 20 x 2
48DJ,DK,FJ,FK,JJ,JK054-074 15...20 x 25 x 2
5...16 x 25 x 2
*See unit Installation Instructions if optional filters are used. When
replacing filters, always use the same type and size originally
supplied.
†For all horizontal supply/return units, filters are field supplied.
Heat Exchanger — To ensure dependable and effi-
cient heating operation, the heat exchanger should be checked
by a qualified maintenance person before each heating sea-
son, and cleaned when necessary. This checkout should not
be attempted by anyone not having the required expertise
and equipment to do the job properly. Checking and/or clean-
ing the heat exchanger involves removing the gas controls
assembly and the flue collector box cover and, when com-
pleted, reinstalling the gas controls assembly for proper op-
eration. Also, the flue collector box cover must be replaced
correctly so that a proper seal is maintained. Contact your
dealer for the required periodic maintenance.
Fans and Belts — Periodically check the condition of
fan wheels and housings, belt tension. When service is nec-
essary, call your dealer.
Indoor Fan Motor, Outdoor Fan Motor and Com-
bustion Fan Motor — Lubrication is not recom-
mended. Bearings will not require lubrication for at least 5
years of normal operation. After 5 years, motor life can be
extended by having the motors serviced at an authorized mo-
tor service shop.
Fan Shaft Bearings — Charge fittings annually with
Shell Alvania #2 or equivalent grease.
Evaporator and Condenser Coils — Cleaning of
the coils should only be done by qualified service personnel.
Contact your dealer for the required annual maintenance.
Condensate Drain — The drain pan and condensate
drain line should be checked and cleaned at the same time
the cooling coils are checked by your dealer.
Compressors — All compressors are factory shipped
with a normal charge of the correct type refrigerant grade oil
in them and should rarely require additional oil. The service
technician must be certain the proper oil level is maintained
in the compressor when it is installed and running.
5

Condenser Fan
Do not poke sticks, screwdrivers, or any other object
into revolving fan blades. Severe bodily injury may
result.
The fan must be kept free of all obstructions to ensure
proper cooling. Contact your dealer for any required service.
Electrical Controls and Wiring — Electrical con-
trols are difficult to check without proper instrumentation;
therefore, if there are any discrepancies in the operating cycle,
contact your dealer and request service.
Refrigerant Circuit — The refrigerant circuit is diffi-
cult to check for leaks without the proper equipment; there-
fore, if inadequate cooling is suspected, contact your dealer
for service.
CombustionArea and Vent System — The com-
bustion area and vent system should be visually inspected
before each heating season. The normal accumulation of dirt,
soot, rust, and scale can result in loss of efficiency and im-
proper performance if allowed to build up.Accumulation on
the pilot crossover tube can result in the burners firing out of
normal time sequence. This delayed ignition is character-
ized by an especially loud sound that can be quite alarming.
If your unit makes an especially loud noise when the
main burners are ignited by the pilot, shut down the heat-
ing section and call your dealer.
See Fig. 1 and 5 and proceed as follows to inspect the
combustion area and power-venting system of your unit.
1. Turn off electrical power and gas supply to your unit.
2. Remove burner compartment access panel. Also, loosen
the bottom screw on cover plate over burner observation
port on unit right side. Move cover plate so that com-
bustion area can be observed.
3. Using a flashlight, carefully inspect the pilot crossover
tube and burner areas for dirt, soot, rust, or scale.
If dirt, soot, rust or scale accumulations are found,
call your dealer and do not operate your heating
section.
48DJ,DK,FJ,FK,JJ,JK034-048
48DJ,DK,FJ,FK,JJ,JK054-074
48MA
Fig. 4 — Panel Locations
6

4. When you have completed your inspection, follow the
start-up procedures in this manual to restore your unit to
restore your unit to operation.
5. Replace burner compartment access panel.
6. Observe unit heating operation, and watch the burner flame
through the observation port to see if it is bright blue. If
you observe a suspected malfunction, or that the burner
flames are not bright blue, call your dealer. See Fig. 6.
NOTE: Burner flames that have a mixture of orange, yel-
low, or red flames together with the blue may not be burn-
ing gas efficiently. Your dealer may have to adjust the air/
gas mixture and/or clean the pilot crossover tube.
7. Reposition cover over burner observation port and tighten
locking screw.
UnitPanels — After performing any maintenance or serv-
ice on the unit, be sure all panels are securely fastened in
place to prevent rain from entering unit cabinet and to pre-
vent disruption of the correct unit airflow pattern.
REGULAR DEALER MAINTENANCE
In addition to the type of routine maintenance you might
be willing to perform, your unit should be inspected regu-
larly by a properly trained service technician. An inspection
(preferably each year, but at least every other year) should
include the following:
1. Inspection of all flue product passages — including the
burners, pilot, heat exchanger, flue collector box, and
vent pipe.
2. Inspection of all combustion- and ventilation-air pas-
sages and openings.
3. Close inspection of all gas pipes leading to and inside
your unit.
4. Adjustment of the air/gas mixture if the burner flames
are not bright blue. (See Fig. 5 and 6 for location of
observation port and proper flame appearance.)
5. Inspection, and if required, cleaning of the evaporator
coils.
6. Inspection, and if required, cleaning of the evaporator
drain pan.
7. Inspection, cleaning, and lubrication of blower wheel hous-
ing and motor.
8. Inspection of all supply-air and return-air ducts for leaks,
obstructions, and insulation integrity.Any problems found
should be resolved at this time.
9. Inspection of the unit base that no cracks, gaps, etc., ex-
ist which may cause a hazard condition.
10. Inspection of the unit casing for signs of deterioration.
11. Inspection of the unit casing for signs of deterioration.
12. Inspection for leaks in the refrigerant circuit. Pressure-
check to determine appropriate refrigerant charge.
13. Operational check of the unit to determine working con-
ditions. Repair or adjustment should be made at this time.
14. Your servicing dealer may offer an economical service
contract that covers seasonal inspections. Ask for fur-
ther details.
Complete Service Instructions can be found in the unit
Installation, Start-Up and Service Instructions.
Fig. 5 — Location of Observation Port
Fig. 6 — Proper Flame Appearance
7

BEFORE YOU CALL FOR SERVICE,
CHECK FOR SEVERAL
EASILY SOLVED PROBLEMS
If insufficient heating or cooling is suspected:
( ) Check for sufficient airflow. Check the air filter for dirt.
Check for blocked return- or supply-air grilles. Be sure they
are open and unobstructed. If these checks do not reveal the
cause, call your servicing dealer.
If your unit is not operating at all, check the following list
for easy solutions:
( ) Check to be sure that your thermostat temperature se-
lector is set above the indoor temperature during the heating
season, or below the indoor temperature during the cooling
season. Be sure the SYSTEM switch is in the proper HEAT
or COOL position and not in the OFF position.
( ) Is the electrical supply switch ON?Are any fuses blown
or has the circuit breaker tripped?
( ) During the heating season, check the external manual
shutoff valve. Is this lever parallel with the pipe, indicating
that the valve is open? Or is the lever at the right angle, in-
dicating that the valve is closed? If closed, has the gas been
shut off for safety reasons? Otherwise, you may open the
valve and follow the start-up procedures listed in this manual.
NOTE: Before proceeding with the next check, turn OFF
the electrical power supply to the unit. Remove the gas sec-
tion access door.
( ) During the heating season, check the control dial on the
gas valve. Is it in the ON position? If it is not, be sure it has
not been turned off for the purpose of safety. If no safety
hazards are present, follow the start-up procedures in this
manual.
( ) If your unit still fails to operate, call your servicing dealer
for troubleshooting and repairs. Specify the model and serial
numbers of your unit. (Record them in this manual in the
space provided.) If the dealer knows exactly which unit you
have, he may be able to offer suggestions over the phone, or
save valuable time through knowledgeable preparation for
the service call.
IN CASE OF TROUBLE
If, after performing the above checks, unit performance is
unsatisfactory, shut off the unit and call your dealer.
Dealer’s Name
Telephone No.
Unit Model
Unit Serial Number
Copyright 1998 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 1
Tab 1a 1c PC 111 Catalog No. 564-920 Printed in U.S.A. Form 48-13SO Pg 8 3-98 Replaces: 48-12SO