B0642moderate severityBody
A/C Compressor Circuit
on 2021 Audi A3 2.0L Turbo I4 · AWD
What this code means
Malfunction in the A/C compressor electrical control circuit.
Symptoms
- A/C not cooling
- Compressor clutch not engaging
- Compressor clutch always engaged
- A/C system cycling abnormally
Common causes
- Faulty compressor clutch coil
- Compressor control valve failure (variable displacement)
- Wiring damage
- Ground circuit issue
- Clutch air gap incorrect
Diagnostic steps
- Test compressor clutch coil resistance
- Check clutch air gap
- Test control valve (if variable)
- Inspect wiring and ground
- Measure voltage at clutch connector
Repair notes
Replace compressor clutch coil or adjust air gap. For variable compressors, replace control valve.
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
B0009
Rear Center Airbag Deployment Circuit
B0010
Driver Side Airbag Deployment