Download 5.- There are at least 5 reasons the compressor clutch will shut-off and not register a DTC: – A/C system is manually turned off. – Ambient temperature too low. – Engine overheat signal from the 4 terminal multi-function temperature sensor. – Load signal from the engine control unit (shut-off for up to 12 seconds). – Kickdown signal from TCM (shut-off for up to 12 seconds). DIAGNOSIS PROCEDURE 1. – Print DTC (additionally, read control head diagnostic display, channel 1, on cars with automatic climate control), then erase DTC. 2. – Check control head coding on cars with automatic climate control. Check compressor clutch control module coding level on cars with manual A/C.