Fault code 25: Diagnosis/troubleshooting

FAULT CODE 25 DIAGNOSIS PROCEDURE

Work instruction			Display OK	If not OK
1	Check 5 V supply lead for short to B+	Switch off ignition Remove plug B from the air-conditioning system regulator Switch on ignition Measure voltage at plug B of the air-conditioning system regulator between pin 20 and ground	0 V Step 2	Repair wiring hamess -> End
2	Check 5 V - supply line	Switch off ignition Replace plug B on the air-conditioning system regulator Remove connector for temperature mixing valve Switch on ignition Measure voltage at plug of the flap motor between pin 3 and ground	approx. 5 V Step 4	If more than 5.5 V is indicated: Step 8 If 0 V is indicated: Step 3
3	Check 5 V supply line for short to ground	Switch off ignition Remove plug B from the air-conditioning system regulator Disconnect plugs from all flap motors Measure resistance at plug B of the air-conditioning system regulator between pin 20 and ground	Step 3	Repair wiring hamess -> End
4	Check potentiometer in the temperature mixing valve.	Measure resistance between pins 1 and 3 of temperature mixing valve	4 - 5 k Step 5	Replace motor for temperature mixing valve. -> End
5	Check potentiometer in the footwell defrost flap	Measure resistance between pins 1 and pin 3 of footwell defrost flap	4 - 5 k Step 6	Replace motor for footwell defrost flap. -> End
6	Check potentiometer in the central flap.	Measure resistance between pins 1 and 3 of the central flap	4 - 5 k Step 7	Repace motor for temperature mixing valve. -> End
7	Check potentiometer in der outside air / recirculation valve	Measure resistance between pins 4 and 5 of the outside air / recirculation air valve	4 - 5 k Step 8	Replace motor for temperature mixing valve. -> End
8	Replace air-conditioning system regulator		->End