DTC Descriptor
WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0645 Air Conditioning (A/C) Clutch Relay Control Circuit
DTC P0646 Air Conditioning (A/C) Clutch Relay Control Circuit Low Voltage
DTC P0647 Air Conditioning (A/C) Clutch Relay Control Circuit High Voltage