VOLVO
ECM-0645 - A/C Clutch Relay Control Circuit
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (5)
- Volvo C30 (2007–2013)2008–2010Engine D4204T only · Transmission MMT6, MPS6 only
- Volvo C70 (2006–2013)2008Engine D4204T only
- Volvo C70 (2006–2013)2009–2010Engine D4204T only · Transmission MMT6, MPS6 only
- Volvo S40 (2004–2013)2008–2010Engine D4204T only · Transmission MMT6, MPS6 only
- Volvo V50 (2004–2013)2008–2010Engine D4204T only · Transmission MMT6, MPS6 only
What does this fault code mean?
The ECM switches the air conditioning relay. The relay gets its supply through the engine system's main relay and is earthed via the control module. If the control module sees no signal, the code is set, and the air conditioning will not work.
Possible causes
- Contact resistance or oxidation in the connections
- Break in the signal wire
- Break in the supply wire to the relay
- Damaged A/C relay
What you can do
- 1Check that the air conditioning fuses are intact in the fuse boxes
- 2Try the A/C controls and see whether the compressor clutch engages
- 3With the ignition off, check the connectors at the relay for looseness, contact resistance and oxidation
- 4Use a multimeter to check the signal and supply wires to the relay for breaks and short circuits to earth
- 5If the fault remains, the relay is probably damaged; a workshop should replace it
Symptoms you may notice1
- Climate control or A/C does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.