Disconnect the A/C pressure switch 4P connector. Turn the ignition switch ON (II). Measure the voltage between the No. 1 terminal of the A/C pressure switch 4P connector and body ground. A/C PRESSURE SWITCH 4P CONNECTOR Wire side of female terminals Is there battery voltage? YES - Go to step 4. NO - Repair open in the wire between the A/C diode A, the ECM and the A/C pressure switch. Turn the ignition switch OFF. Check for continuity between the No. 1 and No. 4 terminals of the A/C pressure switch. A/C PRESSURE SWITCH Is there continuity? YES - Go to step 6. NO - Go to step 10.

Reconnect the A/C pressure switch 4P connector. Disconnect the climate control unit connector A (14P). Turn the ignition switch ON (II). Measure the voltage between the No. 4 terminal of climate control unit connector A (14P) and body ground. CLIMATE CONTROL UNIT CONNECTOR A (14P) Wire side of female terminals Is there battery voltage? YES - Check for loose wires or poor connections at climate control unit connector A (14P) and at the A/C pressure switch 4P connector. If the connections are good, substitute a known-good climate control unit and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Repair open in the wire between the climate control unit and the A/C pressure switch. Check for proper A/C system pressure. Is the pressure within specifications? YES - Replace the A/C pressure switch. NO - Repair the A/C pressure problem. aaa