A/C clutch relay circuit.
With an OBD2 scan tool.
It is under the dash on the left side, forward of the hood release.
The OBD2 diagnostic port is under the dash on the driver side.
Intake Air Temperature Circuit Range/Performance
P0645 AC clutch relay circuit. Possible causes: A/C CLUTCH RLY CIRCUIT WIRING HARNESS OBSERVABLE PROBLEM A/C CLUTCH RLY CIRCUIT WIRING HARNESS INTERMITTENT PROBLEM FUSED IGNITION SWITCH OUTPUT CIRCUIT OPEN A/C CLUTCH RELAY CONTROL CIRCUIT OPEN A/C CLUTCH RELAY CONTROL CIRCUIT SHORT TO GROUND A/C CLUTCH RELAY PCM (A/C CLUTCH RELAY)
With an OBD2 scan tool.
No, 1994 is OBD 1
No, that is for OBD2 cars.
With an OBD2 scan tool.
Under the dash
No. You can not change to OBD 2.
OBD2 connections are usually located underneath the steering column. This could vary from car to car, but it's a good starting location.