Power Supply And Ground Circuit For Front Air Control

TROUBLE DIAGNOSIS


Power Supply and Ground Circuit for Front Air Control

SYMPTOM: A/C system does not come on.

INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - AUTO MODE
1. Press AUTO switch.
2. Display should indicate AUTO. Confirm that the compressor clutch engages (sound or visual inspection).
(Discharge air and blower speed will depend on ambient, in-vehicle and set temperatures.)
Can a symptom be duplicated?
YES - GO TO 3.
NO - GO TO 2.
2.PERFORM COMPLETE OPERATIONAL CHECK
Perform a complete operational check and check for any symptoms. Refer to Operational Check (Front).
Can a symptom be duplicated
YES - Refer to Work Flow.
NO - System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
- GO TO 4.
4.CHECK POWER AND GROUND CIRCUIT
Check main power supply and ground circuit. Refer to "DIAGNOSTIC PROCEDURE FOR A/C SYSTEM".
OK or NG
OK - System OK.
NO - Replace front air control. Refer to Service and Repair.

COMPONENT DESCRIPTION

Front Air Control
The front air control has a built-in microcomputer which processes information sent from various sensors needed for air conditioner operation. The air mix door motors, mode door motor, intake door motors, defroster door motor, blower motor and compressor are then controlled.
The front air control is unitized with control mechanisms. When the various switches and temperature dials are operated, data is input to the front air control.
Self-diagnostic functions are also built into the front air control to provide quick check of malfunctions in the auto air conditioner system.

Potentio Temperature Control (PTC)






There are two PTCs (passenger and driver) (1) built into the front air control. They can be set from 16�C (60�F) to 32�C (90�F) temperature range by rotating the temperature dial. The set temperature is displayed.


DIAGNOSTIC PROCEDURE FOR A/C SYSTEM
SYMPTOM: A/C system does not come on.
1.CHECK POWER SUPPLY CIRCUITS FOR FRONT AIR CONTROL





1. Disconnect front air control connectors.






2. Check voltage between front air control harness connector M49 (A) terminal 15 and connector M50 (B) terminal 27, and ground.






OK or NG
OK - GO TO 2.
NG - Check 10A and 15A fuses [Nos. 2 and 19, located in the fuse block (J/B)]. Refer to Fuse Block-Junction Box (J/B).
- If fuses are OK, check harness for open circuit. Repair or replace as necessary.
- If fuses are NG, replace fuse and check harness for short circuit. Repair or replace as necessary.
2.CHECK GROUND CIRCUIT FOR FRONT AIR CONTROL





1. Turn ignition switch OFF.
2. Check continuity between front air control harness connector M50 terminal 36 and ground.

Continuity should exist.

OK or NG
OK - Replace front air control. Refer to Service and Repair.
NG - Repair harness or connector.