KM50 - No A/C - Attempt to Generate Code 539

- Key "OFF".

- A/C demand switch to "A/C On".

- Perform Key On Engine Off (KOEO) Self-Test. Quick Test Appendix (Detailed Testing Instructions)

- Is KOEO Diagnostic Trouble Code (DTC) 539 present?

Yes -- Go to KM51. KM51 - Check For B+ Voltage to A/C Relay

No -- Go to KM55. KM55 - Check ACD Circuit Continuity to Low Pressure Switch