How to Proceed with Troubleshooting

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Manual Air Conditioning System): Heater Control Switch Circuit

Heater Control Switch Circuit

DESCRIPTION

The No. 3 heater control is powered through the HTR-IG fuse. The No. 3 heater control transmits operational signals of each switch to the A/C amplifier.

WIRING DIAGRAM






INSPECTION PROCEDURE

PROCEDURE

1. INSPECT FUSE (HTR-IG)
(a) Remove the HTR-IG fuse from the instrument panel junction block.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:






NG -- REPLACE FUSE (HTR-IG)
OK -- Continue to next step.

2. INSPECT NO. 3 HEATER CONTROL
(a) Measure the resistance.
(1) Remove the No. 3 heater control.





(2) Disconnect the connector from the No. 3 heater control.
(3) Measure the resistance according to the value(s) in the table below.
Standard Resistance:





HINT: *1: w/ PTC heater
(b) Check that the indicator light comes on.
(1) Connect a positive (+) lead from the battery to terminal 3 and a negative (-) lead from the battery to terminal 4, and check that the indicator light comes on.
OK:
The indicator light comes on.
(c) Check that the illumination comes on.
(1) Connect a positive (+) lead from the battery to terminal 5 and a negative (-) lead from the battery to terminal 6, and check that the illumination comes on.
OK:
The illumination comes on.
NG -- REPLACE NO. 3 HEATER CONTROL
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (NO. 3 HEATER CONTROL - BATTERY)




(a) Measure the voltage according to the value(s) in the table below.
Standard Voltage:





HINT: *1: w/ PTC heater

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (NO. 3 HEATER CONTROL - A/C AMPLIFIER)




(a) Disconnect the connector from the A/C amplifier.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:





HINT: *1: w/ PTC heater

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE