Open circuit, chafed wiring or corroded connector in the clutch feed or control wire; Failed A/C clutch relay or blown fuse in the clutch circuit; Faulty compressor clutch coil (open or shorted winding); Poor earth connection on the clutch or relay circuit; Low refrigerant charge or a pressure switch fault interrupting the clutch circuit; Internal fault in the control unit clutch driver.

P1308

A/C Clutch Circuit Fault.

Other
Powertrain
Manufacturer code
Low severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
3: AreaIgnition system or misfire
08: FaultThe specific fault in that area

What it means

P1308 is a manufacturer-specific code, and on the vehicles that use it for an A/C clutch circuit fault it means the control unit has found a problem in the compressor clutch circuit. It typically sets when the commanded state of the clutch driver or relay does not match the voltage or current the control unit sees, for example an open circuit, a short to ground or a short to power. The exact test conditions vary by make, model and engine, so confirm the definition against manufacturer data for the vehicle.

Symptoms

A/C blowing warm or not cooling
Compressor clutch not engaging when A/C is switched on
Clutch engaging constantly or cycling erratically
Engine management warning light on
Slight idle dip missing when A/C is requested

Possible causes

Open circuit, chafed wiring or corroded connector in the clutch feed or control wirelikely
Failed A/C clutch relay or blown fuse in the clutch circuitlikely
Faulty compressor clutch coil (open or shorted winding)likely
Poor earth connection on the clutch or relay circuitpossible
Low refrigerant charge or a pressure switch fault interrupting the clutch circuitpossible
Internal fault in the control unit clutch driverrare

How to diagnose

Read all stored codes and freeze frame data, and note whether the fault is current or intermittent
Check the A/C clutch fuse and relay, and swap the relay with a known good one of the same type if permitted
Inspect the wiring and connectors from the relay to the compressor for chafing, heat damage, water ingress and corrosion
With the A/C requested, check for battery voltage and a good earth at the clutch connector
Measure the clutch coil resistance and compare it with the manufacturer's specification
Use the scan tool to command the clutch on and off and watch for a response and matching live data
Check the refrigerant pressure and the pressure switch or sensor signal, as low pressure can stop the clutch being energised
Check the wiring between the relay and the control unit for continuity and shorts, then test the control unit output last

How to fix

Repair or replace damaged wiring and clean or replace corroded connectors
Replace the faulty A/C relay or blown fuse, after finding out why it failed
Replace the compressor clutch coil or clutch assembly, or the compressor if the clutch is not available separately
Restore a good earth connection on the clutch or relay circuit
Repair any refrigerant leak, then evacuate and recharge the system to specification
Replace the control unit only after all wiring and component faults have been ruled out

Can I keep driving?

Low severity

The car can normally be driven as the fault mainly affects the air conditioning. Book it in soon, and stop if the compressor is noisy or the drive belt is squealing, because a seized compressor could damage the belt.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.