P0646
Book Code P0646 Inspection
Automotive Climate Control
Low / Normal Under Shade
Code P0646 - A/C Clutch Relay Control Circuit Low
Indicates PCM detected a short-to-ground condition in the A/C clutch relay control coil circuit.
Safe to Drive? ✅ Yes, Safe
Estimated Repair Cost 60 - 250 SAR
Common Makes Generic, Ford, GM, Chrysler, Jeep
System Category relay
Symptoms of Trouble Code P0646:
- ⚠️ AC completely non-operational
- ⚠️ Check Engine light on
- ⚠️ Compressor stationary
Common Causes Behind Code P0646:
- 🔍 Failed AC relay
- 🔍 Control wire rubbed through and shorted to ground
- 🔍 Internal driver fault in PCM
Diagnostic Procedure Recommended by Auto Save Technicians:
- 1 Pull relay and test coil terminals for short circuit
- 2 Check underhood harness for chafing
Specialist Recommendation:
Request Parts & Repair Quote
Swap the relay first before diving into wiring diagnostics.
Associated Components: AC Relay Fuse Box Wiring
Frequently Asked Questions: Code P0646
How can I tell if a relay is bad?
Inspect for burnt smell, shake to listen for broken armature, or test coil resistance with a multimeter across pins 85/86.