Carrier Essential Maintenance Guide for 48TJD Air Conditioner Models

Combustion-Air Blower — Clean periodically to as- sure proper airflow and heating efficiency. Inspect blower wheel every fall and periodically during heating season. For the first heating season, inspect blower wheel bimonthly to deter- mine proper cleaning frequency.

To access burner section, slide the sliding burner partition out of the unit.

To inspect blower wheel, shine a flashlight into draft hood opening. If cleaning is required, remove motor and wheel as follows:

1.Slide burner access panel out.

2.Remove the 7 screws that attach induced-draft motor housing to vestibule plate (Fig. 53).

3.The blower wheel can be cleaned at this point. If addi- tional cleaning is required, continue with Steps 4 and 5.

4. To remove blower from the motor shaft, remove

2 setscrews.

5.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.

6.To reinstall, reverse the procedure outlined above.

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 Controller (IGC) is located in the control box (Fig. 10). The IGC contains 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 uninterrupted. When a break in power occurs, the IGC will be reset (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 Table 31 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 31 — LED Error Code Description*

LED INDICATION	ERROR CODE DESCRIPTION
ON	Normal Operation
OFF	Hardware Failure
1 Flash†	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
LEGEND

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.

†Indicates a code that is not an error. The unit will continue to oper- ate when this code is displayed.

IMPORTANT: Refer to Troubleshooting Tables 32-36 for addi- tional information.

Main Burners — To access burners, remove burner ac- cess panel and slide out burner partition. See Fig. 9. At the beginning of each heating season, inspect for deterioration or blockage due to corrosion or other causes. Observe the main burner flames and adjust, if necessary.

When working on gas train, do not hit or plug orifice spuds.

REMOVAL AND REPLACEMENT OF GAS TRAIN (Fig. 53-55)

1.Shut off manual gas valve.

2.Shut off power to unit.

3.Slide out burner partition. See Fig. 9.

4.Disconnect gas piping at unit gas valve.

5.Remove wires connected to gas valve. Mark each wire.

6.Remove ignitor wires and sensor wires at the Integrated Gas Unit Controller (IGC) (see Fig. 10).

7.Remove the 2 screws that attach the burner rack to the vestibule plate (Fig. 53).

8.Slide the burner tray out of the unit (Fig. 54).

9.To reinstall, reverse the procedure outlined above.

CLEANING AND ADJUSTMENT

1.Remove burner rack from unit as described in Removal and Replacement 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. 55.

5.Reinstall burners on rack.

6.Reinstall burner rack as described in Removal and Replacement of Gas Train section, this page.

Replacement Parts — A complete list of replacement parts may be obtained from any Carrier distributor upon request.

INDUCED-	ROLLOUT
DRAFT	SWITCH
MOTOR
MOUNTING
PLATE

BURNER
SECTION	FLUE
	EXHAUST
	VESTIBULE
INDUCED-	PLATE
DRAFT	BLOWER
MOTOR
	HOUSING
MANIFOLD	GAS
PRESSURE
TAP	VALVE

Fig. 53 — Burner Section Details

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