Duo-Therm 39125 User manual

AIR CONDITIONER & HEAAIR CONDITIONER & HEA
AIR CONDITIONER & HEAAIR CONDITIONER & HEA
AIR CONDITIONER & HEAT PUMPT PUMP
T PUMPT PUMP
T PUMP
SERVICE MANUSERVICE MANU
SERVICE MANUSERVICE MANU
SERVICE MANUALAL
ALAL
AL
This Service Manual is the result of the dedication of The Dometic Cor-
poration and its engineers to providing service people the necessary
instructions for making accurate analysis of certain conditions. Provided
is a comprehensive guide designed to lead a qualified mechanic through
the Service Manual to locate and solve symptoms that may occur.
Dometic continues their commitment to providing the most up to date
information about servicing Duo-Therm Air Conditioners and Heat Pumps.
Form No. 3108892.013 10/00
©2000 The Dometic Corporation
LaGrange, IN 46761
Manual Compliments of
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Table of Contents
Section Page
Installation ......................................................................... A.................................. 1
AC Power Requirements ............................................... A1 ................................ 1
DC Power Requirements .............................................. A2 ................................ 1
Field Wiring ................................................................... A3 ................................ 1
Breaker ......................................................................... A4 ................................ 2
Airbox ............................................................................ A5 ................................ 2
Ducting System ............................................................. A6 ................................ 2
Roof Top Units ........................................................ A6a .............................. 2
Basement Units ...................................................... A6b .............................. 9
Thermostat Location ..................................................... A7 .............................. 12
Operation ........................................................................... B ................................ 14
Air Conditioners ............................................................. B1 .............................. 14
Mechanical Controls ............................................... B1a ............................ 14
Bi-Metal Control System ......................................... B1b ............................ 14
Analog Control System ........................................... B1c ............................ 15
Comfort Control Center System .............................. B1d ............................ 16
Heat Pumps .................................................................. B2 .............................. 22
Mechanical Controls ............................................... B2a ............................ 24
Bi-Metal Control System ......................................... B2b ............................ 24
Analog Control System ........................................... B2c ............................ 25
Comfort Control Center System .............................. B2d ............................ 26
Components ...................................................................... C................................ 27
Motors ........................................................................... C1 .............................. 27
Capacitor, Fan/Run ....................................................... C2 .............................. 28
Capacitor, Start .............................................................. C3 .............................. 28
PTCR Device or Start Relay .......................................... C4.............................. 29
Compressor .................................................................. C5 .............................. 29
Overload Protector ........................................................ C6 .............................. 30
Cold (Freeze) Control .................................................... C7.............................. 30
Electric Heat Strip .......................................................... C8.............................. 30
Selector Switch ............................................................. C9 .............................. 31
Changeover Thermostat ............................................... C10 ............................ 32
Remote Sensor ............................................................. C11 ............................ 32
Ambient Sensor ............................................................ C12 ............................ 33
Reversing Valve ............................................................ C13 ............................ 34
Transformer .................................................................. C14 ............................ 34
Fuse .............................................................................. C15 ............................ 34
Relay ............................................................................. C16 ............................ 35
Printed Circuit Board ..................................................... C17 ............................ 38
Thermostat .................................................................... C18 ............................ 42
Cable Assembly ............................................................ C19 ............................ 52
Sealed System .............................................................. C20 ............................ 55
Wiring ........................................................................... C21 ............................ 58
Other ............................................................................. C22 ............................ 59
Roof Gasket .................................................................. C23 ............................ 60
Configuration ..................................................................... D................................ 60
Symptom/Cause Chart ...................................................... E ................................ 80
Roof Mounted Heat Pumps ........................................... E ................................ 80
Basement Heat Pumps ................................................. E ................................ 93
Roof Mounted Air Conditioners ..................................... E .............................. 102
Basement Air Conditioners ............................................ E ............................... 116
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1
Section A - Installation
A1. AC Voltage
The unit is a 115VAC, 60Hz appliance. The proper operat-
ing range is between 103 and 126.5 volts AC. The voltage
reading should be taken at the unit power supply leads.
One test should be performed when the unit is turned OFF
and another with it running under load. If the voltage is not
within the proper operating range, it must be corrected be-
fore operation of the unit.
This is an energized circuit. Shock can oc-
cur if not tested properly. Testing to be done
by a qualified service technician.
Check for proper AC volts at the connections at the units
electronic control box on roof mounted units and at the
connections at the electric box on basement units.
The dual units (Models 39224 and 39424) have two AC
volt circuits. Verify that Circuit 1 is wired into CIR 1 termi-
nal block and Circuit 2 is wired into CIR 2 terminal block.
Check for proper AC volts at each terminal block.
A1a. AC Control Voltage
AC control voltage is supplied by the transformer for the
control circuits on the following units: 39025.XXX,
39035.XXX and 39045.XXX. Se Section C14- Transform-
ers on page 34.
A2. DC Volts
On certain models of electronic controlled air conditioners
and heat pumps, DC volts must be supplied to the control
board. The operational range is 10 to 16 VDC. If the DC
voltage is below 10 VDC, you could experience improper
operation of the components within the main board.
A2a. Analog Control System
A DC voltage supply is wired to the control board. The
operating range is 10-16 Volts DC, with a maximum cur-
rent draw of 0.250 Amps.
To check DC volts, first check the voltage between the red
(+12) positive and black (-12) negative, at the connections
on the Analog Control Box on the roof top unit.
FIG. A1
If a furnace is to be operated by the Analog Control Sys-
tem, the furnace thermostat leads are connected to the
blue/white striped wires out of the Analog Control Box. The
furnace wires can be connected to either wire as polarity is
not important. DC voltage is required by the Analog Con-
trol Board on one of the two wires for furnace operation.
A2b. Comfort Control Center System
A DC volt supply is required for the operation of the Com-
fort Control Center. The operational range is 10 to 30 volts
DC. If DC volts are outside of the operating range, you
could experience improper or erratic operation. To check
DC volts, first check the incoming DC volts between the
red (+) positive and black (-) negative, at the connections
on the Comfort Control Center control box on roof top units
or at the connections at the electric box of basement units.
A3. Field Wiring
If the unit’s compressor or fan fails to operate, chances are
it is not receiving proper power. Be sure the power cord is
plugged in and fuses ore breakers are ope.
Note: Many customers use extremely long power cords
that are undersized. If possible, ask the owner to hook up
the RV just like it was when the problem occurred. See
FIG. A2
FIG. A2
Make note of the wire size and compare it to the chart for
wire sizing. See Section A1a - AC Control Voltage.
CURRENT WIRE SIZE
IN
AMPS 16 14 12 10 8 6
LENGTH IN FEET
5 47 76 121 192 216 486
10 38 60 96 153 243
15 25 40 64 102 162
20 30 48 76 121
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2
A4. Breaker
Make sure that the power supply to the unit
is disconnected before performing any work
on the unit to avoid the possibility of shock
injury or damage to the equipment.
The unit is to be protected by a time delay fuse or HACR
(heating, air conditioner, refrigerator) breaker. By taking
an amp reading at the unit AC voltage supply line, you can
determine if the breaker is tripping prematurely. Place a
clamp-on type ammeter around the black wire between the
unit and breaker. Turn ON the unit and record the amp
draw. If the breaker trips before the rated amperage, re-
place the breaker.
MODELS CIRCUIT PROTECTION
T.D. Fuse HACR Breaker
39125 (Basement) 15 amp 15 amp
39325 (Basement) 20 amp 20 amp
39224 (Basement) - Circuit 1 15 amp 15 amp
- Circuit 2 15 amp 15 amp
39424 (Basement) - Circuit 1 15 amp 15 amp
- Circuit 2 15 amp 15 amp
All Rooftop Units 20 amp 20 amp
59528.601 15 amp 15 amp
59529.601 15 amp 15 amp
59530.601 15 amp 15 amp
A5. Air Box
Improperly installed, the air box can be a source of cooling
problems. The air box must be sealed to the ceiling tem-
plate to prevent the mixing of discharge and return air. This
will cause short cycling or frost formation on the inside coil
On heat pumps, recirculation can cause the high side pres-
sure to build, tripping the overload and/or breaker. In some
instances, the ceiling template is bent when the anchor bolts
are overtightened, causing gaps between the air box and
the ceiling template. These gaps can be sealed with alu-
minum tape or a closed cell foam weather strip. The duct
connecting the air conditioner or heat pump must be air
tight. Use aluminum tape to seal the joints. The thermo-
stat sensing bulb must be properly located to control tem-
perature. If the sensing bulb is left curled against the side
of the electric box or used as a ground connection, im-
proper operation will occur. Relocate the sensing bulb in
its proper place as indicated in the Installation and Operat-
ing Instructions. Check the air filters and clean.
Section A - Installation, cont’d.
A6. Ducting
A6a. Rooftop Units
Sizing and Design
The installer of this air conditioner system must design the
air distribution system for his particular application. Sev-
eral requirements for this system MUST be met for the air
conditioner to operate properly. These requirements are
as follows:
Roof cavity thickness must be between 2.00" and 5.50".
This distance is measured between roof and ceiling sur-
face.
The total cross-sectional discharge area of the outlet ducts
from the plenum area under the air conditioner must be as
follows:
1. 579 & 600 Series 17.5 sq. in.
2. 591, 595 & 630 Series 21.0 sq. in.
Duct Sizing Requirements as Follows:
Min. Max.
Duct Depth (591/595/630 Series) 1-1/2" 2-1/4"
(579/600 Series) 1-1/4" 2-1/4"
Duct Width 7" — —
Total Duct Length 12 ft. 36 ft.
Duct Length (short run) 1/3 Total Length
Register Requirements as follows:
Min. Max.
Distance from Duct End 5" 8"
Distance from End of Elbow 15" — —
Distance between Registers 24" — —
Total Number Required/AC 4 8
Number Required per Run/AC 2 — —
Free Area per Register 14 sq. in.— —
The duct material must meet or exceed any agency or RVIA
Standard that may be in existence at the time the RV is
produced.
It is the responsibility of the installer of this
system to ensure the ductwork will not col-
lapse or bend during or after the installation.
All discharge air ducts must be properly insulated to pre-
vent condensation from forming on their surfaces or adja-
cent surfaces during operation of the air conditioner or heat
pump. This insulation must be R-7 minimum.
Note: The Dometic Corporation will not be held liable for
roof, structural or ceiling damage due to improperly insu-
lated or sealed ductwork.
Return air opening must have 40 sq. in. minimum free area
including the filter.
Return air to the air conditioner must be filtered to prevent
dirt accumulation on air conditioner cooling surface.
A6a. Roof Top Units
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Total System Pressure must be between the following:
0.55 to 0.90 in. W.C. for 579 Series
0.40 to 1.10 in. W.C. for 591, 595 & 630 Series
0.12 to 0.65 in. W. C. for 600 Series
This is determined with the air conditioner blower opera-
tion on high speed and return air filter and grille in place.
The Dometic Corporation recommends the basic configu-
ration shown below for installing this Air Conditioner Sys-
tem. We have found by testing that this configuration works
best in most applications of the Air Conditioner/Heat Pump
System.
It is the responsibility of the installer of this system to re-
view each RV floor plan and determine the following:
A. Duct Size
B. Duct Layout
C. Register Size
D. Register Locations
E. Thermostat Location
These items must be determined in conjunction with the
Air Distribution System Sizing and Design Requirements
listed.
Note: Alternate configurations and methods may be used
which still allow the air conditioner to operate properly.
However, these alternate configurations and methods must
be approved by The Dometic Corporation in writing.
The following instructions are based upon the use of
Dometic Return Air Kit. The electronic control kit has
mounting bolts supplied for use with this Kit. See FIG. A3.
Before preparing the ceiling opening, the type of system
options must be decided upon. If a remote sensor is to be
used, provisions must be made for it. If the load shed op-
tion (Energy Management System feature) is to be used,
wires must be run from the load shed control to the Dometic
A/C. If a furnace is to be connected, wires must be run
from the furnace to the Air Conditioner.
The 14-1/4" x 14-1/4" (±1/8") opening must be framed to
seal off the roof cavity. Holes used to route electrical wir-
ing should be sealed. The 14-1/4" x 14-1/4" (±1/8") open-
Section A - Installation, cont’d.
ing is part of the return air duct and must be finished in
accordance with NFPA Standard 501C, Standard for Rec-
reational Vehicles, Section 2-7.
The most commonly found installation problem is the im-
proper sealing of the 14-1/4" x 14-1/4" (±1/8") opening in
the roof cavity. The cooled discharge and warm return air
are mixed in the roof cavity and produce conditions that
are excellent for frost production.
Even the best framing job will not stop frost from occurring
if the cold air discharge is allowed to enter into the return
air portion of the 14-1/4" x 14-1/4" (±1/8") opening. See
FIG. A4.
FIG. A3
FIG. A4
Duo-Therm’s return air kits are designed to be installed
tightly to the bottom of the base pan and ceiling template.
Insulation supplied in the kit not only stops condensation
from forming on the divider plate, but prohibits air leaks as
well. The insulation
is purposely over-
sized to be at-
tached to the sides
of the 14-1/4" x 14-
1/4" (±1/8") open-
ing and the base of
the air conditioner
and ceiling tem-
plate. Make sure
the data plate does
not get covered
with insulation.
See FIG. A5.
If a Remote Temperature Sensor is to be used, (Comfort
3
REGISTERS
4 MIN. — 8 MAX. (Per A/C)
14 SQ. IN. FREE AREA
PER REGISTER
14 INCH ROOF
OPENING
ROOF RAFTERS
AIR CONDITIONER
DUCTS MIN. MAX.
DEPTH (590 & 595 Series) 1-1/2" 2-1/4"
(579 & 600 Series) 1-1/4" 2-1/4"
WIDTH 7" — —
TOTAL LENGTH 12' 36'
TOTAL OUTLET
AIR AREA MINIMUM:
17.5 sq. in. - 579 & 600 Series
21.0 sq. in. - 590 & 595 Series
THE MINIMUM SHORT DUCT
RUN MUST EQUAL 1/3 OF
TOTAL DUCT LENGTH
VEHICLE
FRONT
FIG. A5
A6a. Roof Top Units
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REAR REMOTE SENSOR
(Required with Second
Air Conditioner)
REAR REMOTE SENSOR
(Required with Second
Air Conditioner)
14-1/4" x 14-1/4"
(±1/8”) OPENING
14-1/4" x 14-1/4"
(±1/8”) OPENING
14-1/4" x 14-1/4"
(±1/8”) OPENING
14-1/4" x 14-1/4"
(±1/8”) OPENING
OPTIONAL
FURNACE
OPTIONAL
FURNACE
FURNACE
2 WIRES
FURNACE
2WIRES
OPTIONAL FRONT
REMOTE SENSOR
OPTIONAL FRONT
REMOTE SENSOR
12V DC INPUT
2 WIRES
12V DC INPUT
2WIRES
FURNACE
4-CONDUCTOR
CONTROL CABLE
4-CONDUCTOR
CONTROL CABLE
BREAKER BOX
BREAKER BOX
115V AC
REAR A/C
115V AC
REAR A/C
4-CONDUCTOR
CONTROL CABLE
4-CONDUCTOR
CONTROL CABLE
115V AC
FRONT A/C
115V AC
FRONT A/C
FURNACE
2 WIRES
FURNACE
2WIRES
DOMETIC COMFORT
CONTROL CENTER
DOMETIC COMFORT
CONTROL CENTER
4
Section A - Installation, cont’d.
FIG. A6
Control Center configuration, page 16) the connector end
must be routed to the roof opening of the system which it
will control. Make sure that at least 15" of the sensor cable
extends into the roof opening. If a furnace is to be con-
trolled by the system, the two furnace thermostat leads must
be routed to the roof opening of the air conditioner that will
control it. Make sure at least 15" of the furnace thermostat
wires extend into the roof opening. If an Energy Manage-
ment System - EMS (load shed) is to be used with the
control, two wires must be routed to the roof opening of the
zone to be managed. The signal required for this function
is a normally open relay contact. When the EMS calls for
the compressor to shut off, the relay contacts should close.
Make sure that at least 15" of the EMS wires extend into
the roof opening.
FIG. A7
Route a copper 12 AWG, with ground, 115 VAC supply line
from the fuse or circuit breaker box to the roof opening.
a. This supply line must be located in the front portion of
the 14-1/4" (±1/8") opening.
b. The power supply MUST be on a separate Time Delay
Fuse or HACR Circuit Breaker.
c. Make sure at least 15" of supply wire extends into the
roof opening. This ensures easy connection at the
Junction Box.
d. Wiring must comply with all National, State and Local
Wiring Codes.
e. Use a steel sleeve and a grommet or equivalent meth-
ods to protect the wire where it passes into the open-
ing.
Route a dedicated 12 VDC supply line (18-22 AWG) from
the RV’s Converter or Battery to the roof opening.
a. This supply line must be located in the front portion of
the 14-1/4" (±1/8") opening.
b. Make sure that at least 15" of supply wire extends into
the roof opening.
c. In a multiple zone installation, this wiring is required in
only one of the 14-1/4" (±1/8") openings.
Route a 4-conductor telephone cable from the Comfort
Control Center™ mounting position into the 14-1/4" (±1/
8") roof opening. Make sure that at least 15" of the wire
extends into the roof opening and 6" extend from the wall
at the mounting position of the Comfort Control Center™.
In the event that other A/C’s are to be installed (additional
zones) and additional 4-conductor telephone cable must
be routed to the other A/C’s. Make sure that at least 15" of
the wire extends into each of the roof openings. See FIG.
A8.
FRAME
14-1/4" (±1/8”)
OPENING
AC POWER
SUPPLY WIRE
DUCT
FRAME
FRAME
CCC, CONTROL CABLE(S)
or 7-Wire Analog Cable LOW VOLTAGE WIRES:
12VDC
Furnace
Load Shed
Sensors
DUCT
ROOF
INSULATION
DUCT TO REAR CEILING
DUCT TO FRONT
14-1/4" (±1/8”)
OPENING
INSULATION
SIDE VIEW
(TOWARD BACK OF RV)
TOP VIEW
(BACK OF RV)
FIG. A8
A seven-conductor cable, 18-22 AWG is to be used for low
voltage connections for Analog Controls. Choose the short-
est, direct route from the 14" opening to the thermostat
location selected. Consider where screws, nails or staples
might contact the cable. See FIG. A8.
A6a. Roof Top Units
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5
Leave approximately 6" of cable extending through the wall
for connection to thermostat. Leave approximately 10" of
cable extending into the 14-1/4" (±1/8") opening for con-
nection at Relay Kit. See A7 Thermostat Location, page
12.
If System if to control a gas furnace:
Route two 18 AWG from the furnace to 14-1/4" (±1/8") open-
ing at this time.
Section A - Installation, cont’d.
FIG. A9
FIG. A10
FIG. A11
In some installations, the OEM supplies their own return
air kits. Sometimes both the return and the discharge air
are ducted to and from the 14-1/4" x 14-1/4" (±1/8") open-
ing. In some cases the bottom of the 14-1/4" x 14-1/4" (±1/
8") opening is covered with ceiling material.
In this type of installation the 14-1/4" x 14-1/4" (±1/8") open-
ing is divided. If the divider only fills to the thickness of the
ceiling cavity, an air gap may be created both on the top
and bottom of the thickness of the roof gasket, roof or ceil-
ing material. A gasket, etc., must be used to fill up the
open space to reduce recirculation. See FIG. A9.
Another method of connecting the discharge air to the
coach’s main duct used Duo-Therm’s return air kit. It uses
half of the 14-1/4" x 14-1/4" (±1/8") opening as a discharge
plenum. If the duct opening is not clean, restriction of air
can cause the coil to freeze. The opening of the duct should
be as large as possible to make the air distribution better in
the coach and reduce freeze-up. See FIG. A10.
The final method of installation dumps the discharge air
directly into the RV’s main duct. The duct is routed through
the 14-1/4" x 14-1/4" (±1/8") opening. A duct adapter is used
to connect the air conditioner to the main duct. If this con-
nection is not made properly, cold air can migrate back into
the return air path and make conditions right for freeze-up.
Be sure the duct adapter is sealed to the main duct and air
conditioner. See FIG. A11.
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Restrictions at the connection to the air conditioner is the
most common cause, but blockage in the main duct runs
can also cause freeze-up. Blockages commonly occur in
the areas where the duct changes direction. Other ob-
stacles that can cause a change in the duct (air) path in-
clude rafters, vent pipes, wire bundles, etc. See FIG. A12.
A good way to check for duct blockage is with a flashlight
and a mirror. Remove ceiling register cover to allow a flash-
light to be put in the duct and use a mirror to view the flash-
light from the next register opening. A blockage will be
visible in the mirror. See FIG. A12.
Duo-Therm has available a quick cool return air kit that will
allow the cooled air to come directly out of the air condi-
tioner. This will bypass any restrictions in the coach duct
system. (Part No. 3105958.007 Shell White, 3105958.015
Polar White).
If the main duct in the vehicle is undersized, the volume of
air flowing through the ducts will decrease. The coil tem-
perature will also drop because not enough air is moving
through it. The requirements for proper duct size are shown
in FIG. A13.
Section A - Installation, cont’d.
Up to this point we have mainly covered the discharge side;
however, restrictions of the return air can result in frost
buildup. The Duo-Therm air conditioner requires a mini-
mum of 40 square inches of FREE AREA.
FREE AREA - is the opening that remains in a grill or lou-
vered panel after the restrictions are taken away. For ex-
ample, an opening of 10 x 20 inches has 200 square inches.
When this opening is covered with a grill that is 56 percent
open, the FREE AREA is (200 x .56), 112 square inches.
Dometic return air kits are designed to have the correct
free area; however some manufacturers use their own grills.
If a manufacturer’s grill is used, it must use the above for-
mula to make sure the return air is sufficient to reduce the
chances for freeze-up. The filter material must also be con-
sidered as a restriction and subtracted from the FREE
AREA. See FIG. A14.
Main ducts running through the 14-1/4" x 14-1/4" (±1/8")
opening must leave space between the duct and return air
grill or duct and bottom of the air conditioner. See FIG.
A15, A16, A18.
REGISTERS
4 MIN. — 8 MAX. (Per A/C)
14 SQ. IN. FREE AREA
PER REGISTER
14 INCH ROOF
OPENING
ROOF RAFTERS
AIR CONDITIONER
DUCTS MIN. MAX.
DEPTH (590 & 595 Series) 1-1/2" 2-1/4"
(579 & 600 Series) 1-1/4" 2-1/4"
WIDTH 7" — —
TOTAL LENGTH 12' 36'
TOTAL OUTLET
AIR AREA MINIMUM:
17.5 sq. in. - 579 & 600 Series
21.0 sq. in. - 590 & 595 Series
FIG. A13
FIG. A12
FIG. A14
THE MINIMUM SHORT DUCT
RUN MUST EQUAL 1/3 OF
TOTAL DUCT LENGTH
"S" PATTERN DUCT SYSTEM
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7
Section A - Installation, cont’d.
FIG. A16
FIG. A15
FIG. A17
FIG. A18
The gap between the top and the main duct to the bottom
of the air conditioner should be a minimum of 1-1/2". See
FIG. A17 & A18.
If the return air is ducted into the 14-1/4" X 14-1/4" (±1/8")
opening, the duct must be equal to the 40 sq. inches that
are needed by the air conditioner. Grill or registers used
ing this duct must be equal to or greater than the duct in
square inches.
The control system used by Duo-Therm Air Conditioner is
designed with a low temperature switch that will shut off
the compressor and allow air to flow through the coil to
melt the frost. A properly operating cold control may allow
a slight coating of frost to form on the evaporator coil be-
fore it turns off the compressor. If the cold control is not
installed in its intended mounting locations, frost buildup
can block all air flow through the evaporator coil and stop
cooling inside the RV. The cold control has clips that allow
it to be snapped onto the turn/bends of the evaporator coil.
See FIG. A20 & A21 for the correct location.
A6a. Roof Top Units
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Freeze Control Installation
579, 590 & 595 Series:
a. Snap freeze control into place on return bend located
at left side of evaporator coil as follows:
1) Locate “D” shaped notch in flange of evaporator
coil.
2) Place the horseshoe end of freeze control through
this notch and snap onto coil return bend. When
positioned correctly, control wires will be 90° to di-
rection of coil fin surface. See FIG. A20
Note: Freeze control is not used on heat pump coils. Some
will have the “D” slot in the coil header.
Section A - Installation, cont’d.
FIG. A19
Freeze Control with wires.
Coil
Return
Bend
Do
kdkd
mfmf
Remove
Hang
Tag
600 SERIES
579, 590 & 595 SERIES FIG. A21
FIG. A20
Mount the Freeze Control on left side
of coil, with wires to the right side
Install Freeze Control with wires as shown
Freeze Control Installation
600 Series:
a. Snap the freeze control into place on return end lo-
cated at right side of evaporator coil as follows:
1) Locate vertical return bend at lower right of evapo-
rator coil.
2) Place the horseshoe end of freeze control onto this
coil return bend and snap into place. When posi-
tioned correctly, control wires will be 90° to direc-
tion of coil fin surface. See FIG. A21.
Note: Freeze control is not used on heat pump coils, some
8
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Section A - Installation, cont’d.
will have the “D” slot in the coil header.
A6b. Basement Units
Models 39335 and 39125
Outdoor Section:
The Condenser coil is designed to have a fresh supply of
air. If skirting is installed, allow a louvered grill with 330
square inches for supply air and a louvered grill on oppo-
site side of coach (330 square inches) for discharge air.
Do not totally enclose the underside of the
unit. Air circulation prevents heat from build-
ing under unit and your system will perform
as designed.
The condenser section is a “blow-through” type. When the
face of the coil is positioned behind a louvered or other
type of restrictive opening, the FREE AREA of the opening
must be at least 260 square inches.
FREE AREA - is the opening that remains in a grill or lou-
vered panel after the restrictions are taken away. For ex-
ample, an opening of 10 x 20 inches has 200 square inches.
When this opening is covered with a grill that is 56 percent
open, the FREE AREA is (200 x .56), 112 square inches.
Expanded and perforated metal grills in general vary from
30 percent to 60 percent open. Be certain that 260 square
inches of FREE AREA is available to the face of the con-
denser.
Note: Service access must always be supplied either as
clearance or as a defined access panel.
Mounting
Vibration eliminators are supplied to prevent the transmit-
tance of vibration into the living area.
The air conditioning unit may be attached to rails beneath
the vehicle, attached to the frame, or mounted directly to
the floor of some vehicles.
Unit should be mounted with a tilt toward the rear (con-
denser) a half-bubble using a level. Unit rear should be 1/
4" lower than the front.
Service Access
Be sure NOT to block the inlet or discharge air, or service
access, when mounting.
Indoor Section:
Clearances
The minimum clearances to the evaporator are zero inches
to the bottom, top, left and right sides. Access to the elec-
trical connections and drain connection must be provided
when making the installation.
Be sure to allow sufficient room to service
the electrical components.
Inlet Air
The evaporator section must have free access to room air.
A minimum or 180 square inches of FREE AREA open-
ing is required. Where the return air must be provided
through louvers or mesh scree, the FREE AREA percent-
age of the material used shall be taken into consideration
when making this determination. An example of how to
determine FREE AREA is included under “Outdoor Sec-
tion”.
Grills and Registers
Note: The return air grill must have the same square sur-
face as the coil face (15"H x 17"L).
For each air conditioning system, there must be a return
grill to bring cabin air back into the unit. There must also
be at least four discharge grills per unit.
Each return air grill must be filtered and accessible for clean-
ing and replacement.
Outlet Air
The central air conditioning unit is designed to use a dis-
charge air duct with a static pressure of .10 to .25 inches
water column. Proper duct size is necessary to maintain
proper air flow without loss of static pressure and provide
good air circulation.
All air handling ducts must be properly insulated to prevent
condensation forming on their surface during operating. A
vapor barrier must also be supplied on the outer surface of
the insulation to prevent moisture from traveling through
the insulation and condensing on the cold ductwork.
Note: If the air conditioning unit is attached to the central
furnace, a damper must be installed at the furnace outlet
to prevent cold air from circulating through the furnace heat
exchanger, unless furnace is so equipped to utilize the built-
in furnace relay.
A6b. Basement Units
Manual Compliments of
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RETURN SYSTEM
-Risers use interior wall structure
-Using floor joists area for return to unit
-Each return grill is filtered
FIG. A22
10
Section A - Installation, cont’d.
RETURN
RISER X 2
2" X 12" INSULATED
DUCT (MIN.)
90 SQ. IN.
FILTERED
(MIN. X 2)
DISCHARGE
CONDENSER
AIR
SUPPLY AIR
INSULATED
2" X 10" CLOSEABLE
GRILL (MIN. X 4))
MIN. 180 SQ. IN.
REQUIRED OPENING
ENCLOSED
FLOOR JOIST
FLOORING
FLOOR CUTOUT
90 SQ. IN. MINIMUM
FLOOR CUTOUT
90 SQ. IN. MINIMUM
Models 39224 and 39424
Condenser Section:
Supply Air
The inlet of the condenser coil should be positioned so that
it draws air from outside the vehicle. Special care must
be taken to prevent the discharge air from recirculat-
ing to the inlet of the condenser coil. Shields should be
added to ensure fresh air supply.
Do not install the condenser where the fan
will draw air from the exhaust of the vehicle,
a motor generator set, transmission, road
heat or ANY other heat producing source.
FIG. A23
FIELD INSTALLED SHIELD THAT WILL PREVENT
RECIRCULATION OF CONDENSER AIR.
The condenser section is a “draw-through” type. When the
face of the coil is positioned behind a louvered or other
type of restrictive opening, the FREE AREA of the opening
must be at least 460 square inches.
A6b. Basement Units
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11
Section A - Installation, cont’d.
FREE AREA - is the opening that remains in a grill or lou-
vered panel after the restrictions are taken away. For ex-
ample, an opening of 10 x 20 inches has 200 square inches.
When this opening is covered with a grill that is 56 percent
open, the FREE AREA is (200 x .56), 112 square inches.
Expanded and perforated metal grills in general vary from
30 percent to 60 percent open. Be certain that 460 square
inches of FREE AREA is available to the face of the con-
denser.
Note: Service access must always be supplied either as
clearance or as a defined access panel.
Clearances
The air conditioning unit clearances depend on:
1. Inlet air access used
2. Discharge air duct arrangement
3. Return air duct
4. Storage compartment location and design
A one (1) inch clearance is required on three (3) sides of
the air conditioner if the top return is used. When using the
side access for return, please allow a minimum of eight (8)
inches for the return air duct. Access to the electrical con-
nections must be provided when making the installation.
Evaporation Section:
Inlet Air
The evaporation section must have free access to room
air. A minimum of 128 square inches of FREE AREA open-
ing is required. Where the return air must be provided
through louvers or mesh screen, the FREE AREA percent-
age of the material used shall be taken into consideration
when making this determination. An example of how to
determine FREE AREA is included under Condenser Sec-
tion. See FIG. A24.
Supply Duct must be insulated.
Supply Duct from air conditioner
must be equal to or greater
in IN.2as the floor ductwork.
Use 45 degree angle on inlets
& outlets
Electrical box access required.
Each circuit, 15 AMP HACR
breaker
REGISTER REQUIREMENTS
REQ. SIZE MIN. QTY.
4 X 6 4
4 X 8 4
4 X 10 4
4 X 12 4
ADDITIONAL REQUIREMENTS:
Damper required in furnace.
Vibration isolators should be
used at each mounting point.
12 VDC required for Comfort
Control operation.
INSULATED DUCT
Minimum Maximum
40 IN. 260 IN. 2
(3 " depth Min.)
Optional return area.
May be used in
conjunction with side
return.
FIG. A24
Condenser air outlet ( X2 in bottom)
Must be isolated from condenser inlet air.
Condenser inlet air 2 places.
RETURN SYSTEM
Return to be 6 ft. minimum from floor.
Use wall structure for delivery to basement area.
Return grille must be filtered.
Minimum return required per duct sizing for unit to
perform within Engineering specifications. See Chart below:
DUCT SIZE MINIMUM MAX.
40 IN. 2128 IN. 2189 IN. 2
60 IN. 2128 IN. 2189 IN. 2
A6b. Basement Units
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12
Section A - Installation, cont’d.
Grills
Note: The Return air grill must have the same square sur-
face as the return air duct.
1. For each air conditioning system, there must be a re-
turn grill to bring cabin air back into the unit. There
must also be at least four discharge grills per unit.
2. Return grills must be mounted in front of the evapora-
tor. If this is not possible, make sure there is nothing
blocking the air flow from the grill to the evaporator.
3. The unit must have a return filter between the grill and
the unit. This filter must be accessible for periodic clean-
ing.
Outlet Air
The air diffusion system, supplied by the installer, must be
sized to maintain a static pressure at the blower outlet be-
tween .4 and 1.2 inches water column.
All air handling ducts must be properly insulated to prevent
condensation forming on their surface during operation. A
vapor barrier must also be supplied on the outer surface of
the insulation to prevent moisture from traveling through
the insulation and condensing on the cold ductwork. See
section A6a - Rooftop Units.
A7. Thermostat Location
The thermostat location is very important for balanced
temperature control in any RV.
Today’s interior design has become both cosmetically more
appealing and more efficient in its use of storage space.
These improvements have generated complex interior
space requirements which, in turn, have caused many RV’s
to become a maze for heating and air conditioning circula-
tion.
The heating system is usually mounted close to floor level
and consists of one or more furnaces. The air conditioner(s)
is mounted on the roof with a different air distribution sys-
tem. It is very important to locate the thermostat and re-
mote sensors in areas that have good air movement. This
may be difficult because what works well for heating may
not work well for air conditioning.
The thermostat or remote sensors must be placed in a lo-
cation with good air movement. Placing a thermostat or
sensor under a cabinet or in a corner will result in a large
fluctuation in the temperature. See FIG. A25.
FIG. A25
The proper location for the thermostat or remote sensor is
54" from the floor and on an inside wall. It should be lo-
cated where it cannot be affected by heat from the sun,
lamps, oven, etc., or other sources of draft. Locations close
to entry doors and windows should be avoided. The dis-
charge from registers blowing directly on the thermostat or
remote sensor can cause the system to short-cycle and
should be avoided. See FIG. A26.
FIG. A26
Examples of Bad Thermostat Locations
1, 3, 4 Near Heat Sources
2 Near Drafts or Heat source
5, 6 Near Drafts
7 On an Outside Wall
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13
Section A - Installation, cont’d.
When the floor plan or interior design of an RV changes,
Dometic suggests trying several locations for the thermo-
stat or remote sensor to determine the best location for
mounting. Both heating and air conditioning should be
tested, especially when using different duct systems and
the same thermostat. When the proper thermostat or re-
mote sensor location is determined, this location can be
used on other RV’s with the same basic plan. See FIG.
A27.
FIG. A27
Example of
Good Thermostat Location
(Interior Hallway Wall)
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14
Section B - Operation
B. Operation
The recreational vehicle manufacturer has equipped the
vehicle with Duo-Therm’s Air Conditioner. The ability of
the unit to maintain the desired inside temperature depends
on the heat gain of the RV. Some preventative measures
can be taken by the occupants of the RV to reduce the
heat gain and improve the performance of the unit. During
extremely high outdoor temperatures, the heat gain of the
vehicle may be reduced by:
1. Parking the RV in a shaded area.
2. Using window shades (blinds and/or curtains).
3. Keeping windows and doors shut or minimizing usage.
4. Avoid use of heat producing appliances.
5. Starting the unit early in the morning and giving it a
“head start” on the expected high outdoor tempera-
tures will greatly improve its ability to maintain the de-
sired indoor temperature.
The operating instructions can change from one model to
another.
Be sure you are familiar with the proper operating instruc-
tions for the specific model of air conditioner you are diag-
nosing. An installation and operating manual is packaged
with each air conditioner system.
B1. Air Conditioners
B1a. Mechanical Controls
This type of air conditioner has an air distribution box that
has a mechanical selector switch and thermostat installed
in it.
Controls
The Selector Switch has eight positions including “OFF”.
This controls fan speed, heating mode and cooling modes.
The Thermostat controls the temperature range from 65°F
on the coldest side to 90°F on the warmest side. In the
cooling mode, the compressor ON/OFF is controlled by
the thermostat setting. See FIG. B1.
Mechanical Cooling Operation
Set the thermostat at the desired temperature level. Se-
lect the fan speed that best satisfies your needs. See FIG.
B1.
a. HIGH COOL - Selected when maximum cooling
and dehumidification is required.
b. MED. COOL - Selected when normal or average
cooling is required.
c. LOW COOL - Selected when room is at desired
comfort level and needs to be maintained. Nor-
mally this speed is used for nighttime operation.
Note: The blower runs continuously to circulate air and
maintain an even temperature. The compressor will come
on as cooling is required to maintain the selected tempera-
ture level.
After shutting the air conditioner down with
either selector switch or thermostat, wait at
least two (2) minutes before restarting. This
allows the refrigerant pressure to equalize
and compressor to restart easily.
Fan Operation
This will circulate the air in your RV without cooling or heat-
ing. There are three positions: HIGH FAN, MED. FAN or
LOW FAN to select from, depending upon personal choice.
Heating Operation
(With Optional Heat Kit Installed)
Note: This electric heater will not replace a furnace for
heating your RV in cold weather. The intent is to remove
the chill on cool days or mornings.
1. Turn the selector switch to “OPT. HEAT”.
2. The heater will come on and begin heating.
3. When desired temperature level in RV is reached, move
the selector switch to off position or fan position.
Note: Thermostat does not control heater ON/OFF cycle.
“OFF” Position turns unit off. See FIG. B1.
B1b. Bimetal Relay Controls
This type of air conditioner has a wall mounted bimetal ther-
mostat and a relay board that replaces the mechanical
switch and thermostat on the mechanical units and replaces
the main board and control board on the electronic units.
Note: Remember to check the installation and operating
instructions for the specific model of air conditioner you
are diagnosing.
FIG. B1
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1
3
4
2
15
Cooling Operation
Place the Temperature Set Lever to desired temperature
level (located at top of thermostat). Select fan speed that
best satisfies your needs: (upper right switch at bottom of
thermostat). See FIG. B2.
a. High Speed: Selected when maximum cooling and
dehumidification are required.
b. Low Speed: Selected when RV reaches desired com-
fort level and needs to be maintained. Normally this
speed is used for nighttime operation.
Select Auto/ON Switch operation as follows:
(Lower right switch at bottom of thermostat)
a. Auto Position: Air conditioner fan runs whenever cool-
ing is required and stops whenever cooling is not re-
quired.
b. On Position: Air conditioner fan runs continuously to
circulate air in RV.
Set the Heat/OFF/Cool Switch to cool position
(Located at lower left side of thermostat)
The air conditioner will now come on when cooling is re-
quired and cycle off when the temperature level selected is
reached.
1 = Temp Set Lever
2 = Auto/ON Switch
3 = System Switch
4 = Fan Speed
Section B - Operation, cont’d.
Wait at least two (2) minutes before restart-
ing the air conditioner after shutting off with
either the Heat/OFF/Cooling Switch of the
Temperature Set Lever. This allows the refrig-
erant pressure in the air conditioner to equal-
ize and will allow the compressor to restart
easily.
Heating Operation
(If furnace is connected to Thermostat)
Set Temperature Set Lever to desired temperature level
(located at top of thermostat). See FIG. B2.
Set the Heat/Off/Cool Switch to heat position (located at
lower left side of thermostat). See FIG. B2.
The furnace will now come on when heat is required and
cycle off when temperature level selected is reached.
Special Feature
When thermostat:
Heat/Off/Cool Switch is in the OFF or HEAT position
and Auto/On Switch is in the ON position, the air con-
ditioner fan will run continuously to circulate the air in-
side the RV. See FIG. B2.
B1c. Analog Control System
In order to familiarize yourself with the operation of the
Analog Control System, the following diagrams along with
the accompanying text will explain all the functional char-
acteristics of the system.
FIG. B2 FIG. B3
B1b. Bimetal Relay Controls
SYSTEM
FAN
ON
AUTO
HI
LO
COOL
OFF
FURNACE
HEAT PUMP
90
80
70
60
50
40
30
20
10
°C
1
2
34
SYSTEM
FAN
ON
AUTO
HI
LO
COOL
OFF
FURNACE
HEAT PUMP
90
80
70
60
50
40
30
20
10
°C
HEAT STRIP
SYSTEM
FAN
ON
AUTO
HI
LO
COOL
OFF
FURNACE
HEAT PUMP
90
80
70
60
50
40
30
20
10
°C
1. Temperature Set Lever
2. Fan Auto/On Switch
3. System Switch
4. Fan High/Low Switch
Analog Control Cooling Operation
1. Place the Temperature Set Lever (1) to desired tem-
perature level. See FIG. B3.
2. Select desired fan speed by moving the Fan Speed
Switch (4) to :
a. High speed: Selected when maximum cooling and
dehumidification are required.
b. Low speed: Selected when RV reaches desired
comfort level and needs to be maintained. Nor-
mally this speed is used for night time operation.
3. Move the FAN Auto/On Switch (2): See FIG. B3
a. Auto Position: Unit fan runs whenever cooling is
required and stops whenever cooling is not re-
quired.
b. ON Position: Unit fan runs continuously to circu-
late air in RV. See FIG. B3.
4. Set the System Switch to cool position. The unit com-
pressor will now come ON and cycle OFF when the
temperature level selected is reached.
Furnace Operation
(If furnace is connected to relay box.)
1. Set the Temperature Set Lever (1) to desired tem-
perature setting. See FIG. B3
2. Set the System Switch (3) to furnace position. The
furnace will now come ON when heat is required and cycle
OFF when the temperature setting selected is reached.
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16
Section B - Operation, cont’d.
Analog Control Electric Heat Strip Operation
(If unit is equipped with optional electric heat strip.)
1. Set the Temperature Set Lever (1) to desired tem-
perature level. See FIG. B3.
2. Set the System Switch (3) to heat strip position.
3. Move the FAN Auto/On Switch (2):
a. Auto Position: Unit fan runs whenever heat is
required and stops whenever heating is not re-
quired. See FIG. B3.
b. ON Position: Unit fan runs continuously to circu-
late air in RV. See FIG. B3.
4. Select desired fan speed by moving the Fan Speed
Switch (4) to:
a. High Speed: Selected when maximum air flow is
required. The discharge air will feel cool due to the
maximum air flow. It is normally not used for heat
strip operation. See FIG. B3.
b. Low Speed: Normally selected for heat strip op-
eration, because less air movement is needed for
heat and discharge air is warmer. See FIG. B3.
5. Set System Switch (3) to the heat strip position. The
unit’s heat strip will now come “ON” and cycle “OFF”
when the temperature level selected is reached.
Continuous Blower Operation
1. Set the System Switch (3) to any position (including
“OFF”). See FIG. B3.
2. Move the FAN Auto/On Switch (2) to the ON position,
the unit fan will operate continuously at the fan speed
selected by the Fan Speed Switch (4). See FIG. B3.
B1d. Comfort Control Center
The Comfort Control Center has been designed for you to
easily operate all the air conditioning and gas heating ap-
pliances found in your vehicle from one location.
In order to familiarize yourself with the operation of the
Comfort Control Center, the following diagram along with
A. Liquid Crystal Display
B. Fan Speed Selector Button
C. Mode Selector Button
D. Temperature Selector Buttons
E. Zone and Stage Selector
F. On/Off Switch
FIG. B4
the accompanying text will explain all the functional char-
acteristics of the system.
Liquid Crystal Display - The Comfort Control Center is
equipped with a liquid crystal display (LCD) that identifies
the mode of operation, the temperature set-point, the zone
identification and the fan speed. The Comfort Control Cen-
ter is designed to accept and control many varied air con-
ditioning and gas heating appliances. When you begin to
first operate the Comfort Control Center, you will see that
the LCD readout will only show the options available based
on the appliances installed on your vehicle. An incandes-
cent light will illuminate the LCD area when a selector but-
ton is pushed for easy reading at all times. See FIG. B4.
Fan Speeds - Possible available fan speeds are: LOW,
MEDIUM, HIGH and AUTO. To select the desired fan speed,
momentarily depress the FAN push button. You will need
to continue to depress and release the FAN button until the
desired fan speed is shown in the LCD readout area of the
Comfort Control Center. See FIG. B4.
Mode Selector Button - Modes of operation available are:
OFF, FAN ONLY, COOL, HEAT PUMP, FURNACE, STAGE
and HEAT STRIP. Remember, the LCD readout will only
show the options available based on the appliances installed
on your vehicle. To select the mode of operation, momen-
tarily depress the MODE push-button. You will need to
continue to depress and release the button until the de-
sired mode is shown in the LCD readout area on the Com-
fort Control Center. See FIG. B4
To determine the Comfort Control Center options available
to you, depress and release the MODE push-button until it
goes through all selections. See FIG. B4
Temperature Selector Buttons - The temperature set-
point range is from 40° to 99° Fahrenheit. Determination
of Fahrenheit or Celsius standard is done at the time of
your manufacturer’s installation of the Comfort Control
Center. To set the temperature at your comfort level, sim-
ply depress and release the UP or DN push-button until the
desired temperature is shown in the LCD readout area of
the Comfort Control Center. See FIG. B4
Zone and Stage Selector Buttons - A ZONE is also es-
tablished at the time of installation of the Comfort Control
Center. If you have one air conditioner, you will have one
ZONE. If the vehicle has more than one cooling system,
depending on the manufacturing installation, you may have
2, 3 or 4 ZONES. Zones are defined and preset by the
manufacturer. A zone is an area of cooling/heating which
is controlled independently within that area, and regulated
at the Comfort Control Center. A typical example of a two
zone application would be a vehicle with two air condition-
ing systems, one in the front area (living room, kitchen)
and one in the back section (bedroom and bath). The front
area could be established as ZONE 1 and the back section
ZONE 2. You can select the desired temperature and fan
speeds for each zone independently, thereby keeping your
bedroom cooler than the front portion of the vehicle. To
determine the number of established zones in the vehicle,
simultaneously depress the FAN and MODE push-buttons.
ZONE 1 will be the first Zone to appear in the LCD readout.
Continue to depress and release these buttons until you
see ZONE 1 reappear. See FIG. B4.
B1d. Comfort Control Center
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17
Section B - Operation, cont’d.
ON/OFF Switch - The ON/OFF switch is located on the
lower right hand edge of the Comfort Control Center. Move
the lever from side to side to change status. See FIG. B5.
General Information
The ability of the air conditioner to maintain the desired
inside temperature depends on the heat gain of the RV.
Some preventative measures taken by the occupants of
the RV can reduce heat gain and improve the performance
of the air conditioner. During extremely high outdoor tem-
peratures, the heat gain of the vehicle may be reduced by:
1. Parking the RV in a shaded area.
2. Using window shades (blinds and/or curtains).
3. Keeping windows and doors shut or minimizing usage.
4. Avoiding the use of heat producing appliances.
Starting the air conditioner early in the morning and giving
it a “head start” on the expected high outdoor ambient will
greatly improve its ability to maintain the desired indoor
temperature.
The manufacturer of this air conditioner will not be respon-
sible for damage caused by condensed moisture on ceil-
ings or other surfaces. Air contains moisture and this mois-
ture tends to condense on cold surfaces. When air enters
the RV, condensed moisture may appear on the ceiling,
windows, metal parts, etc. The air conditioner removes
this moisture from the air during normal operation. Keep-
ing doors and windows closed when the air conditioner is
in operation will minimize condensed moisture on cold sur-
faces.
This equipment must be serviced by qualified personnel
and some states require these people to be licensed.
Fan Only Mode of Operation - See FIG. B4 & B5
1. Begin by placing the power switch on the lower right
hand edge of the Control Center in the ON position.
To do this, simply move the lever to the right.
2. Momentarily depress and release the MODE push-
button until the FAN ONLY indicator on the Liquid
Crystal Display (LCD) is illuminated.
3. Momentarily depress and release the FAN push-
button until the desired fan speed indicator (LOW, MED,
HIGH, AUTO) is illuminated. If your vehicle is equipped
with a heat pump or a dual basement air conditioning
system, your selection choice will be LOW, HIGH or
AUTO.
4. After approximately 5 seconds, the selected fan speed
will come on. The MODE and FAN speed you have
selected will remain shown in the LCD area of the Con-
trol Center until you change your selection.
5. If the vehicle contains more than one ZONE, depress
the FAN and MODE push-buttons simultaneously to
select ZONE 2, and repeat procedures from step two
above. Repeat entire procedure for each additional
zone.
Cooling Mode Operation - See FIG. B4 & B5
(To set cooling temperatures and fan speeds on Duo-Therm
Air Conditioners and the cooling mode of Duo-Therm Heat
Pumps.)
1. Momentarily depress and release the MODE
push-button until the COOL indicator on the LCD is
illuminated.
2. Depress and release the FAN push-button to select
your desired fan speed.
3. Depress and release the UP push-button to increase
the temperature or the DN push-button to decrease
the desired temperature. The final selected SETPOINT
will be displayed in the LCD area of the Comfort Con-
trol Center.
4. After a delay of approximately 2 minutes the air
conditioner’s compressor will come on and the cooling
process will begin. Once the room temperature
reaches the selected SETPOINT, the compressor will
cycle off. Once the Comfort Control Center senses the
need for cooling, the compressor will restart in approxi-
mately two minutes. At this point, the fan will either:
a. continue to operate in the single selected fan speed
or,
b. cycle OFF and ON with the compressor if the AUTO
fan speed has been selected.
If the vehicle has a dual basement air conditioner or
dual heat pump system, the word STAGE (see stage
operation, page 20) will be illuminated. Both of these
units operate in two different stages, and the word
STAGE will show when the second stage operation has
been selected. To select the second stage, simulta-
neously depress the FAN and MODE push-buttons.
See FIG. B4 & B5.
FIG. B5
B1d. Comfort Control Center
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18
Section B - Operation, cont’d.
Fan Only Mode of Operation - See FIG. B4 & B6
1. Begin by placing the power switch on the lower right
hand edge of the Control Center in the ON position.
To do this, simply move the lever to the right.
2. Momentarily depress and release the MODE
push-button until the FAN ONLY indicator on the Liq-
uid Crystal Display (LCD) is illuminated.
3. Momentarily depress and release the FAN push-
button until the desired fan speed indicator (LOW, MED,
HIGH, AUTO) is illuminated. If your vehicle is equipped
with a heat pump or a dual basement air conditioning
system, your selection choice will be LOW, HIGH or
AUTO.
4. After approximately 5 seconds, the selected fan speed
will come on. The MODE and FAN speed you have
selected will remain shown in the LCD area of the Con-
trol Center until you change your selection.
5. If the vehicle contains more than one ZONE, depress
the FAN and MODE push-buttons simultaneously to
select ZONE 2, and repeat procedures from step two
above. Repeat entire procedure for each additional
zone.
FIG. B7
Cooling Mode Operation
(To set cooling temperatures and fan speeds on Duo-Therm
Air Conditioners and the cooling mode of Duo-Therm Heat
Pumps.) See FIG. B7.
1. Momentarily depress and release the MODE
push-button until the COOL indicator on the LCD is
illuminated.
2. Depress and release the FAN push-button to select
your desired fan speed.
3. Depress and release the UP push-button to increase
the temperature or the DN push-button to decrease
the desired temperature. The final selected SETPOINT
will be displayed in the LCD area of the Comfort Con-
trol Center.
4. After a delay of approximately 2 minutes the air
conditioner’s compressor will come on and the cool-
ing process will begin. Once the room temperature
reaches the selected SETPOINT, the compressor will
cycle off. Once the Comfort Control Center senses the
need for cooling, the compressor will restart in approxi-
mately two minutes. At this point, the fan will either:
a. continue to operate in the singe selected fan speed
or,
b. cycle OFF and ON with the compressor if the
AUTO fan speed has been selected.
5. If the vehicle contains more than one ZONE, depress
the FAN and MODE push-buttons simultaneously to
select ZONE 2, and repeat procedures from Step 1.
Repeat entire procedure for each additional zone.
Note: If set point is too low, the inside could freeze up.
72
FIG. B6
B1d. Comfort Control Center
Manual Compliments of
Northwest RV Supply
Printed From
http://www.nwrvsupply.com