X55 - Check Continuity:Cyclic Pressure Switch & CCRM or ACPSW

- Key "OFF".

- Cyclic pressure switch disconnected.

- Constant Control Relay Module (CCRM) disconnected.

- AC Pressure Switch (ACPSW) disconnected (if applicable).

- For vehicles that use R-12 refrigerant:

- Measure resistance between the A/C demand circuit to CCRM pin at the cyclic pressure switch vehicle harness connector and Pin 21 of the CCRM vehicle harness connector.

- All others:

- Measure resistance between the A/C demand circuit to ACPSW at the cyclic pressure switch vehicle harness connector and the A/C demand/cyclic pressure switch input pin at the ACPSW vehicle harness connector.

- Is resistance less than 5.0 ohms?

Yes -- Reconnect CCRM. Go to Heating and Air Conditioning to check the operation of the cyclic pressure switch. After any service, reconnect all components and re-evaluate symptom.

No -- Service open circuit. Reconnect all components. Re-evaluate symptom.