Theory Of Operation
WARNING: This page is about a different car, the 2012 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The A/C clutch control is requested by the Powertrain Control Module (PCM) along the A/C clutch control relay circuit. The Totally Integrated Power Module (TIPM) monitors the sense voltage on the A/C clutch relay circuit, when PCM pulls the circuit low the TIPM engages the A/C clutch. If the sense voltage is missing or pulled low the PCM will set the P0645-A/C CLUTCH RELAY CIRCUIT DTC.