Evaporator Temperature Sensor / Switch: Testing and Inspection

Use a volt/ohmmeter to test the electronic cycling clutch switch. Verify that the refrigerant system has the correct refrigerant charge. Check that both the low and high pressure cut-off switches are functional as described before testing the electronic cycling clutch switch.
1. Disconnect and isolate the battery negative cable. Unplug the wire harness connectors at the electronic cycling clutch switch and the high pressure cut-off switch. Check for continuity between the C9OA circuit cavities in the body half of the electronic cycling clutch switch wire harness connector and the high pressure cut-off switch wire harness connector. There should be continuity. If OK, go to Step 2. If not OK, repair the open circuit as required.
2. Unplug the wire harness connector at the low pressure cut-off switch. Check for continuity between the C2 circuit cavities in the body half of the electronic cycling clutch switch wire harness connector and the low pressure cut-off switch wire harness connector. There should be continuity. If OK, go to Step 3. If not OK, repair the open circuit as required.
3. Plug in the wire harness connectors at the low pressure cut-off and high pressure cut-off switches. Connect the battery negative cable. Turn the ignition switch to the ON position. Check for battery voltage at the fused ignition switch output (run) circuit cavity in the body half of the electronic cycling clutch switch wire harness connector. If OK, go to Step 4. If not OK, repair the open circuit to the junction block as required.
4. Plug in the wire harness connector at the electronic cycling clutch switch. With the ambient temperature from 20 to 30 °C (68 to 90 °F), start the engine and set the heater-A/C mode control switch in any A/C position. If the compressor clutch fails to engage, use a DRB III scan tool and the proper Diagnostic Procedures to check the Powertrain Control Module (PCM) and its inputs and outputs. If the compressor clutch engages, the clutch should cycle ON and OFF two to three times per minute. If the clutch fails to cycle at this rate in these ambient temperatures, replace the faulty electronic cycling clutch switch.

NOTE: If the ambient temperature is above 32 °C (90 °F) the compressor clutch may stay engaged and not cycle due to the high heat load. This condition is normal.