For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: HVAC Schematics
1 | Did you review the Air Delivery Description and Operation and the Air Temperature Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual
2 |

1. Start the engine.
2. Turn the blower switch to the OFF position.
3. Turn the A/C switch to the OFF position.

Does the compressor clutch disengage?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3 | Disconnect the compressor clutch relay. Does the compressor clutch disengage? | Go to Step 5 | Go to Step 4
4 | Test for a short to voltage in the compressor clutch supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 9
5 | Exchange the compressor clutch relay with a known good relay (the horn relay or the shiftlock relay). Does the compressor clutch operate normally? | Go to Step 10 | Go to Step 6
6 |

1. Reconnect the compressor clutch relay.
2. Disconnect the compressor control module connector.

Does the compressor clutch engage?

Go to Step 7

Go to Step 8

7 | Test for a short to ground in the compressor clutch relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 11
8 | Test for a short to ground in the A/C request signal circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 11
9 | Replace the A/C compressor clutch. Refer to Air Conditioning Clutch Coil Replacement . Did you complete the replacement? | Go to Step 12 | --
10 | Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement . Did you complete the replacement? | Go to Step 12 | --
11 | Replace the A/C compressor control module. Refer to Air Conditioning (A/C) Compressor Control Module Replacement . Did you complete the replacement? | Go to Step 12 | --
12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3