
FULL-AUTOMATIC AIR CONDITIONER –
Troubleshooting
55-38
Code No.31 Potentiometer system of air mix damper motor
assembly
Probable cause
This diagnosis code is output if no signals are input from air mix damper potentiometer
to A/C-ECU because of short-circuit or open-circuit in the harness.
D
Malfunction of the air mix damper potentiometer
D
Malfunction of connector, harness
D
Malfunction of the A/C-ECU
Air mix damper potentiometer check (Refer to P.55-59.)
NG
Replace
OK
Measure at the air mix damper potentiometer connector B-39.
D
Disconnect the connector, and measure at the harness
side connector.
D
Voltage between terminal (6) and body earth
OK: 5 V
NG
Check the following connector:
B-04
NG
Repair
OK
Check the trouble symptom.
NG
Check the harness between the air mix damper potentiometer
and the A/C-ECU.
NG
Repair
OK
Replace the A/C-ECU.
OK
Measure at the A/C-ECU connector B-04.
D
Connect the connector.
D
Air mix damper position: MAX.HOT
D
Voltage between terminal (5) and body earth
OK: 4.7 – 5.0 V
NG
Check the following connector:
B-39
NG
Repair
OK
Check the trouble symptom.
NG
Check the harness between the air mix damper potentiometer
and the A/C-ECU, and repair if necessary.
OK
Check the following connector: B-04
NG
Repair
OK
Check the trouble symptom.
NG
Replace the A/C-ECU.