XB53 - Check A/C System Pressure Change

- Key "OFF".

- Install A/C System Manifold Gauge Set. Refer to Heating and Air Conditioning.

- A/C "OFF".

- Start engine.

- Note the A/C high pressure gauge reading.

- While monitoring the A/C high pressure gauge reading, turn the A/C "ON". Ten seconds after clutch engagement, note the pressure (the pressure should increase).

- Key "OFF".

- A/C "OFF".

- Did the A/C high pressure gauge reading change more than 20 psi within 10 seconds of clutch engagement?

Yes -- Go to XB54 (the A/C pressure changed as expected. ACP sensor and circuit will now be checked). XB54 - Check ACP Sensor Output

No -- A/C system pressure did not change as expected. Go to Heating and Air Conditioning to check for A/C system mechanical concerns. After any service, clear continuous memory. Clearing Diagnostic Trouble Codes

Attempt to reset Diagnostic Trouble Code (DTC) 579 (refer to XB52 for procedure only). XB52 - Clear and Attempt to Regenerate DTC

Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)