A/C Compressor Power Relay

Using an ohmmeter, ensure continuity is not present between terminals No. 1 and 3. Ensure continuity is present between terminals No. 2 and 4.
When battery power is applied to terminal No. 2 and terminal No. 4 is grounded, continuity should be present between terminals No. 1 and 3. See Fig 1 .

Fig 1: A/C Compressor Relay Terminal Identification

Courtesy of CHRYSLER MOTORS.