B0640moderate severityBody
A/C Compressor Clutch Relay Circuit
on 2007 Mercedes-Benz S65 AMG 6.0L V12 BiTurbo M275 · RWD
What this code means
Malfunction in the A/C compressor clutch relay circuit. The relay controls engagement of the A/C compressor.
Symptoms
- A/C not blowing cold air
- Compressor clutch not engaging
- A/C works intermittently
- Relay clicking
Common causes
- Faulty A/C clutch relay
- Relay control circuit issue
- Low refrigerant triggering cutoff
- BCM or PCM relay driver failure
- Corroded relay socket
Diagnostic steps
- Check A/C clutch relay
- Test relay with jumper wire
- Check refrigerant pressure
- Test relay control signal from PCM/BCM
- Inspect relay socket for corrosion
Repair notes
Replace A/C clutch relay. If relay keeps failing, check compressor clutch current draw.
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Other Body codes on this vehicle
B0001
Driver Frontal Stage 1 Deployment Control
B0002
Driver Frontal Stage 2 Deployment Control
B0003
Passenger Frontal Stage 1 Deployment Control
B0004
Passenger Frontal Stage 2 Deployment Control
B0005
Driver Knee Airbag Deployment Circuit
B0006
Passenger Knee Airbag Deployment Circuit
B0007
Rear Left Side Airbag Deployment Circuit
B0008
Rear Right Side Airbag Deployment Circuit
B0010
Driver Side Airbag Deployment
B0011
Driver Side Airbag Deployment Circuit Open