A/C Compressor Clutch Output Circuit Malfunction (GM)
What does P1194 mean?
The P1194 code means the vehicle's onboard diagnostic system has detected: A/C Compressor Clutch Output Circuit Malfunction (GM). This is a low severity code.
Common Symptoms
- Check Engine Light on
- A/C not engaging or blowing warm air
- A/C compressor clutch not clicking on
- Intermittent A/C operation
- No cold air from vents
Probable Causes (Ranked by Likelihood)
- Failed A/C compressor clutch relay Very High
- Open or short in A/C clutch wiring High
- Faulty A/C compressor clutch coil Moderate
- Low refrigerant causing pressure switch to prevent clutch engagement Moderate
- PCM A/C clutch driver circuit failure Low
Step-by-Step Diagnostic Procedure
-
Check the A/C compressor clutch relay in the fuse box
-
Verify the A/C system has adequate refrigerant pressure
-
Test the clutch coil resistance at the compressor connector
-
Check for power and ground at the clutch coil connector when A/C is commanded on
-
Inspect wiring between the PCM, relay, and compressor for damage
Frequently Asked Questions
Can low refrigerant cause P1194?
Low refrigerant itself may not set P1194, but if the low-pressure switch opens due to low refrigerant, the PCM may interpret this as a clutch circuit issue. Always check refrigerant levels as part of the diagnosis.
How do I test the A/C clutch coil?
Disconnect the electrical connector at the compressor. Measure the clutch coil resistance with a multimeter. It should typically read 3 to 5 ohms. An open reading (infinity) means the coil is burned out.
Is the A/C clutch replaceable separately?
On many GM vehicles, the A/C clutch assembly can be replaced without removing the compressor. This includes the clutch plate, coil, and pulley. This is much less expensive than replacing the entire compressor.