Carrier 48LJD - Manual (Page 24)

Flue Gas Passageways — To inspect the flue col­
lector box and upper areas of the heat exchanger:
1. Remove the combustion blower wheel and motor assem­
bly according to directions in Combustion-Air Blower
section below.
2. Remove the 3 screws holding the blower housing to the
flue cover.
3. Remove the flue cover to inspect the heat exchanger.
4. Clean all surfaces as required using a wire brush.
Combustion-Air Blower — Clean periodically to as­
sure proper airflow and heating efficiency. Inspect blower
wheel eveiy fall and periodically during heating season. For
the first heating season, inspect blower wheel bimonthly to
determine proper cleaning frequency.
To inspect blower wheel, remove draft hood and screen.
Shine a flashlight into opening to inspect wheel. If cleaning
is required, remove motor and wheel as follows:
1. Slide burner access panel out.
2. Remove the 2 screws which hold the heat shield in place,
and remove heat shield.
3. Remove the 7 screws that attach induced-draft motor mount­
ing plate to blower housing (Fig. 36).
4. Slide the motor and blower wheel assembly out of the
blower housing. The blower wheel can be cleaned at
this point. If additional cleaning is required, continue
with Steps 5 and 6.
5. To remove blower from the motor shaft, remove 2 set­
screws.
6. To remove motor, remove the 4 screws that hold the
motor to mounting plate. Remove the motor cooling fan
by removing one setscrew. Then remove nuts that hold
motor to mounting plate.
7. To reinstall, reverse the procedure outlined above.
ROLLOUT
SWITCH'
^ FLUE
EXHAUST
BLOWER
HOUSING
GAS
VALVE
Fig. 36 — Burner Section Details
Limit Switch — Remove blower access panel (Fig. 6).
Limit switch is located on the fan deck.
Burner Ignition — Unit is equipped with a direct spark
ignition 100% lockout system. Integrated Gas Unit Control­
ler (IGC) is located in the control box (Fig. 11). IGC con­
tains a self-diagnostic LED (light-emitting diode). A single
LED on the IGC provides a visual display of operational or
sequential problems when the power supply is uninter­
rupted. When a break in power occurs, the IGC will be re­
set (resulting in a loss of fault history) and the indoor
(evaporator) fan ON/OFF times will be reset. The LED
error code can be observed through the viewport. During
servicing refer to the label on the control box cover or Ta­
ble 17 for an explanation of LED error code descriptions.
If lockout occurs, unit may be reset by interrupting power
supply to unit for at least 5 seconds.
Table 17 — LED Error Code Description*
LEO INDICATION ERROR CODE DESCRIPTION
ON Normal Operation
OFF Hardware Failure
1 Flasht Evaporator Fan On/Off Delay Modified
2 Flashes Limit Switch Fault
3 Flashes Flame Sense Fault
4 Flashes 4 Consecutive Limit Switch Faults
5 Flashes Ignition Lockout Fault
6 Flashes Induced-Draft Motor Fault
7 Flashes Rollout Switch Fault
8 Flashes Internal Control Fault
LED — Light-Emitting Diode
*A 3 second pause exists between LED error code flashes, if more
than one error code exists, all applicable codes will be displayed in
numerical sequence
flndicates a code that is not an error. The unit will continue to op­
erate when this code is displayed.
IMPORTANT: Refer to Troubleshooting Tables 19-22 for addi­
tional information.
Main Burners — At the beginning of each heating sea­
son, inspect for deterioration or blockage due to corrosion
or other causes. Observe the main burner flames and ad­
just, if necessary.
 CAUTION
When working on gas train, do not hit or plug orifice
spuds.
REMOVAL OF GAS TRAIN (Fig. 36 and 37)
1
.
2 .
3.
4.
5.
6
.
7.
8
.
10 .
11
.
12 .
Shut off manual gas valve.
Shut off power to unit.
Remove compressor access panel (not shown).
Slide out burner section side panel (not shown).
Remove heat shield.
Disconnect gas piping at unit gas valve.
Remove wires connected to gas valve. Mark each wire.
Remove induced-draft motor, ignitor, and sensor
wires at the Integrated Gas Unit Controller (IGC) (see
Fig. 11).
Remove the 2 screws that attach the burner rack to the
vestibule plate.
Remove the gas valve bracket.
Slide the burner tray out of the unit (Fig. 37).
To reinstall, reverse the procedure outlined above.
CLEANING AND ADJUSTMENT
1. Remove burner rack from unit as described in Removal
of Gas Train section, above.
2. Inspect burners; if dirty, remove burners from rack.
3. Using a soft brush clean burners and cross-over port as
required.
4. Adjust spark gap. See Fig. 38.
5. Reinstall burners on rack.
6. Reinstall burner rack as described in Replacement of Gas
Train section, above.
Replacement Parts — A complete list of replace­
ment parts may be obtained from any Carrier distributor
upon request.
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