Carrier 48GX, 48GS User Manual
Combination Gas Heating/
Electric Cooling Units
A Guide To Operating and Maintaining Your
Gas Heating/Electric Cooling Unit
48GS,GX
NOTE TO INSTALLER
This manual should be left with the equipment owner.
FOR YOUR SAFETY
Do not store or use gasoline or other
flammable vapors and liquids in the vicinity of this or any other appliance.
Improperinstallation,adjustment,alteration,service or maintenance can cause injury or propertydamage. Refer to this manual. For assistance
or additional information, consult a qualified installer, service agency, or the gas supplier.
FOR YOUR SAFETY
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Donot touch any electrical switch; do not
use any phone in your building.
• Immediately call your gas supplier from
a neighbor’sphone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier,
call the fire department.
Before performing recommended maintenance,
be sure gas supply and main power switch to
unit are turned off.Electrical shock could cause
personal injury.
Model 48GS with Standard Wire Grille
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 4
Tab 1a 6a
PC 111 Catalog No. 534-742 Printed in U.S.A. Form 48GS,GX-1SO Pg 1 3-99 Replaces: 48GS-1SO
Model 48GX with Optional Louvered Grille
Your combination heating/cooling unit is equipped with
an automatic direct sparkignitionandpowercombustionblower .
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, familiarize yourself with all the procedures that must
be followed.
If you do not follow these instructions exactly, a fire or
explosion may result, causing property damage, injury,
or loss of life.
Refer to Fig. 1. See Fig. 2 for location of gas valve. Refer
to Fig. 3 while proceeding with the following steps.
Step 1 — Set the temperature selector on room thermo-
stat to the lowest temperature setting and set system switch
to HEAT.
Step 2 — Close the external manual shutoff valve.
Step 3 — Turn off the electrical supply to the unit.
Step 4 — Remove the front access panel with a
nut driver.
5
⁄16-in.
Step 5 — Move the selector switch on the internal gas
valve to the OFF position and wait 5 minutes.
Step 6 — Move the selector switch on the internal gas
valve to the ON position.
Step 7 — Replace the front access panel.
Step 8 — Turn on the electrical supply to unit.
Step 9 — Open the external manual shutoff valve.
Step 10 — Set the temperature selector on room thermo-
stat slightly above room temperature to start unit. The induceddraft combustion-air fan will start. Main gas valve will open
and main burners should ignite within 5 seconds. If the burner
does not light within 5 seconds, the ignition module will go
into a Retry mode after a period of approximately 22 seconds (following the 5-second ignition period).
If the burners do not light within 15 minutes of the initial
call for heat, there is a lockout.
Step 11 — Set the temperature selector on room ther-
mostat to desired setting.
FRONT
ACCESS
PANEL
Fig. 1 — Gas Heating/Electric Cooling Unit
(Unit 48GS Shown)
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.
NOTE: If unit is being shut down because the heating season has ended, make sure to turn on power to cooling
system.
If unit is being shut down because of a malfunction, call
your dealer as soon as possible.
Should overheating occur or the gas supply fail to shut
off, shut off the manual gas valve to the unit before shutting
off the electrical supply.
Do not use this unit if any part has been under water. Immediately call a qualified service technician to inspect the
unit and to replace any part of the control system and any
gas control which has been under water.
Refer to Fig. 4 while proceeding with the following steps.
Step 1 — Set the temperature selector on room thermo-
stat to lowest temperature setting and set system switch to
OFF.
Step 2 — Close the external manual shutoff valve.
1. If the main burners fail to light, or the blower fails
to start, shut down gas heating section and call your
dealer for service.
2. Never attempt to manually light the main burners on
unit with a match, lighter, or any other flame. If the
electric sparking device fails to light the main burners, refer to the following shutdown procedures, then
call your dealer as soon as possible.
Failure to follow these requirements could result in serious
personal injury.
Step 3 — Turn off the electrical power supply to the unit.
Step 4 — Remove the front access panel.
Step 5 — Move the selector switch on the internal gas
valve to the OFF position.
Step 6 — Replace the burner access panel.
Step 7 — Restore electrical power to the unit and set sys-
tem switch to COOL to ensure operation of the cooling system during the cooling season.
2
ROUTINE MAINTENANCE
All routine maintenance should be handled by skilled, experienced personnel. Your dealer can help you establish a
standard procedure.
For your safety, keep the unit area clear and free of combustible materials, gasoline, and other flammable liquids and
vapors.
To assure proper functioning of the unit, flow of combustion and ventilating air must not be obstructed from reaching
the unit. Clearance of at least 30 in. is required on all sides
except the duct side.
MAINTENANCE AND 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 panels or performing maintenance functions inside your unit, be aware of sharp
sheet metal parts and screws. Although special care
is taken to reduce sharp edges to a minimum, be extremely careful when handling parts or reaching into
the unit.
Air Filters — Air filter(s) should be checked at least ev-
ery 3 or 4 weeks and changed or cleaned whenever it becomes dirty.Dirty filters produce excessive stress on the blower
motor and can cause the motor to overheat and shut down.
Table 1 indicates the correct filter size for your unit. Refer
to Fig. 5 to access the filter(s).
To replace or inspect filter(s) (or accessory filter rack when
supplied):
1. Remove the filter access panel using a
2. Remove the filter(s) by pulling the filter(s) out of the unit.
If the filter(s) is dirty, clean or replace with new one.
When installing the new filter(s), note the direction of the
airflow arrows on the filter frame.
If you have difficulty in locating your air filter(s), or if
you have questions concerning proper filter maintenance, contact your dealer for instructions. When replacing filters, always use the same size and type of filter that was supplied
originally by the installer.
5
⁄16-in. nut driver.
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 efficiency and, in some cases, fire.
Heat Exchanger — To ensure dependable and efficient
heating operation, the heat exchanger should be checked by
a qualified maintenance person before each heating season,
and cleaned when necessary. This checkout should not be
attempted by anyone not having the required expertise and
equipment to properly do the job. Checking and/or cleaning
the heat exchanger involves removing the gas controls assembly and the flue collector box cover and, when completed, reinstalling the gas controls assembly for proper operation. 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 Fan Motor — Periodically check the con-
dition of fan wheels and housings and fan-motor shaft
bearings. No lubrication of condenser- or evaporator-fan
bearings or motors is required or recommended.
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.
Compressor— All compressors are factory-shipped with
a normal charge of the correct type refrigeration grade oil in
them and should rarely require additional oil. The service
person must be certain the proper oil level is maintained in
the compressor when it is installed and running.
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.
Table 1 — Indoor-Air Filter Data*
UNIT SIZE FILTER SIZE
48GS018-030 20x20
48GS036-042 20x24
48GS048-060 24x30
48GX024-030 20x20
48GX036 20x24
48GX042-060 24x30
*For filter grille installations only.
Fig. 2 — Gas Heating/Electric Cooling Unit
3
STEP 1
STEP 2
STEP 3
STEP 6
STEP 4
STEP 5
STEP 7
STEP 8
STEP 9
Fig.3—ToLight Unit
4
STEP 10
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