For 1990-2009 cars

Table 1: | Compressor Control Module Voltage Table

Step | Action | Yes | No
--- | --- | --- | ---
1 | Was the HVAC System Check performed? | Go to Step 2 | Go to HVAC System Check
2 |

Important: Before performing this diagnostic, verify that the air conditioning (A/C) refrigerant system is in the correct mechanical condition in order to avoid a misdiagnosis.Inspect the refrigerant level.Inspect the system for leaks.

1. Disconnect the A/C compressor clutch connector.

Start the engine.

2. Press the A/C switch to the ON position.
3. Move the blower speed selector switch to any position except the OFF position.
4. Connect a test lamp between the terminal of the A/C compressor clutch connector and ground.

Does the test lamp light?

Go to Step 3

Go to Step 4

3 | Replace the A/C compressor clutch. Refer to Compressor Clutch Coil Replacement . Is the repair complete? | Go to HVAC System Check | --
4 |

1. Remove the relay box from the wheelhousing.
2. Backprobe the connector of the A/C compressor clutch relay with a test lamp from terminal 3 to ground.

Does the test lamp light?

Go to Step 5

Go to Step 6

5 | Repair the open in the BLK/RED wire between the A/C compressor clutch relay and the A/C compressor clutch. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to HVAC System Check | --
6 | Backprobe the connector of the A/C compressor clutch relay with a test lamp from terminal 4 to ground. Does the test lamp light? | Go to Step 8 | Go to Step 7
7 | Repair the open in the RED/WHT wire between the A/C fuse and the A/C compressor clutch relay. Is the repair complete? | Go to HVAC System Check | --
8 | Backprobe the connector of the A/C compressor clutch relay with a test lamp from terminal 1 to ground. Does the test lamp light? | Go to Step 10 | Go to Step 9
9 | Repair the open in the LT GRN wire between the junction block and the A/C compressor clutch relay. Is the repair complete? | Go to HVAC System Check | --
10 |

1. Disconnect the connector of the A/C compressor control module.
2. Connect a fused jumper wire to the connector of the A/C compressor control module from terminal 7 to ground.

Does the A/C compressor clutch engage?

Go to Step 11

Go to Step 12

11 | Connect a test lamp to the connector of the A/C compressor control module from terminal 8 to ground. Does the test lamp light? | Go to Step 16 | Go to Step 15
12 | Backprobe the connector of the A/C compressor clutch relay with a fused jumper wire from terminal 2 to ground. Does the compressor clutch engage? | Go to Step 14 | Go to Step 13
13 | Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement . Is the repair complete? | Go to HVAC System Check | --
14 | Repair the open in the PNK wire between the A/C compressor clutch relay and the A/C compressor control module. Is the repair complete? | Go to HVAC System Check | --
15 | Repair the open in the BLK/WHT wire between S202 and the A/C compressor control module. Is the repair complete? | Go to HVAC System Check | --
16 | Connect a test lamp to the connector of the A/C compressor control module from terminal 3 to B+. Does the test lamp light? | Go to Step 18 | Go to Step 17
17 | Repair the open in the BLK/BLU wire or in the BLK wire between terminal 3 of the A/C compressor control module and G201. Is the repair complete? | Go to HVAC System Check | --
18 | Connect a test lamp to the connector of the A/C compressor control module from terminal 9 to B+. Does the test lamp light? | Go to Step 20 | Go to Step 19
19 | Repair the open in the BLK wire between terminal 9 of the A/C compressor control module and G201. Is the repair complete? | Go to HVAC System Check | --
20 | Connect a test lamp to the connector of the A/C compressor control module from terminal 11 to ground. Does the test lamp light? | Go to Step 22 | Go to Step 21
21 | Backprobe the connector of the A/C switch with a test lamp from terminal 2 to ground. Does the test lamp light? | Go to Step 24 | Go to Step 23
22 | Connect a test lamp to the connector of the A/C compressor control module from terminal 12 to B+. Does the test lamp light? | Go to Step 27 | Go to Step 28
23 | Backprobe the connector of the A/C switch with a test lamp from terminal 1 to ground. Does the test lamp light? | Go to Step 25 | Go to Step 26
24 | Repair the open in the BLU/WHT wire between the A/C switch and the A/C compressor control module. Is the repair complete? | Go to HVAC System Check | --
25 | Replace the A/C switch. Refer to Air Conditioning (A/C) Cooling Fan Switch Replacement . Is the repair complete? | Go to HVAC System Check | --
26 | Repair the open in the PNK/BLK wire between S233 and the A/C switch. Is the repair complete? | Go to HVAC System Check | --
27 |

1. Disconnect the evaporator temperature sensor connector.
2. Connect a J 39200 to the connector of the evaporator temperature sensor from terminal 1 to terminal 2.
3. Measure the resistance at room temperature.

Is the resistance greater than 2000 ohms?

Go to Step 32

Go to Step 33

28 |

1. Disconnect the refrigerant pressure switch.
2. Connect a test lamp to the connector of the refrigerant pressure switch between terminal 1 and B+.

Does the test lamp light?

Go to Step 29

Go to Step 31

29 | Inspect for an open in the ORN/BLK wire between the A/C compressor control module and the refrigerant pressure switch. Did you find an open? | Go to Step 39 | Go to Step 30
30 | Replace the refrigerant pressure switch. Refer to Pressure Cycling Switch Replacement . Is the repair complete? | Go to HVAC System Check | --
31 | Repair the open in the BLK wire between the refrigerant pressure switch and G103. Is the repair complete? | Go to HVAC System Check | --
32 | Replace the evaporator temperature sensor. Refer to Air Conditioning (A/C) Temperature Sensor Replacement . Is the repair complete? | Go to HVAC System Check | --
33 |

1. Reconnect the evaporator temperature sensor.
2. Connect a J 39200 from connector terminal 4 of the A/C compressor control module to connector terminal 10 of the A/C compressor control module.
3. Measure the resistance.

Is the resistance greater than 2000 ohms?

Go to Step 34

Go to Step 35

34 | Repair the open in the WHT/BLU wire or in the YEL/GRN wire between the A/C compressor control module and the evaporator temperature sensor. Is the repair complete? | Go to HVAC System Check | --
35 |

1. Disconnect the powertrain control module (PCM) connector C3.
2. Connect a J 39200 to the connector of the A/C compressor control module from terminal 5 to ground.
3. Measure the resistance.

Is the resistance infinite?

Go to Step 37

Go to Step 36

36 | Repair the short to ground in the LT GRN/RED wire between the PCM and the A/C compressor control module. Is the repair complete? | Go to HVAC System Check | --
37 |

1. Reconnect the PCM connector C3.
2. Back out the LT GRN/RED wire from terminal 5 of the connector of the A/C compressor control module.
3. Connect the connector of the A/C compressor control module.
4. Disconnect the A/C compressor clutch connector.
5. Connect a test lamp between the connector terminal of the A/C compressor clutch and ground.

Does the test lamp light?

Go to Air Conditioning (A/C) Idle Circuit Diagnosis 1.0L or Air Conditioning (A/C) Idle Circuit Diagnosis 1.3L in Engine Controls

Go to Step 38

38 | Replace the A/C compressor control module. Refer to Air Conditioning (A/C) Compressor Control Module Replacement . Is the repair complete? | Go to HVAC System Check | --
39 | Repair the open in the ORN/BLK wire between the A/C compressor control module and the refrigerant pressure switch. Is the repair complete? | Go to HVAC System Check | --

#### Compressor Control Module Voltage Table

Terminal/Wire | Circuit | Normal Value | Condition
--- | --- | --- | ---
1/BLU/RED | A/C idle-up control | 0-1 Volt | The ignition switch, the blower switch, and the A/C switch are ON.
10-14 Volts | The ignition switch is ON.
2 | Not Used
3/BLK/BLU | Ground | 0-1 Volt | The ignition switch is ON.
4/WHT/BLU | Evaporator temperature input | 1.2-1.5 Volts (2107-2575 ohms | The evaporator temperature is approximately 15°C (59°F) with the ignition switch ON.
2.1-2.4 Volts (4609-5095 ohms) | The evaporator temperature is approximately 0°C (32°F) with the ignition switch ON.
5/LT GRN/RED | A/C cutout signal | 10-14 Volts | The blower switch and the A/C switch are ON with the engine running.
0-1 Volt | The ignition switch is ON.
6 | Not Used
7/PNK | Compressor clutch relay control | 0-1 Volt | The blower switch and the A/C switch are ON with the engine running.
10-14 Volts | The ignition switch is ON.
8/BLK/WHT | Ignition power | 10-14 Volts | The ignition switch is ON.
9/BLK | Ground | 0-1 Volt | The ignition switch is ON.
10/YEL/GRN | Evaporator temperature sensor ground | 0-1 Volt | The ignition switch is ON.
11/BLU/WHT | A/C request signal | 10-14 Volts | The ignition switch, the blower switch, and the A/C switch are ON.
0-1 Volt | The ignition switch is ON, and the blower switch or the A/C switch is OFF.
12/ORN/BLK | Refrigerant pressure switch signal | 0-1 Volt | The refrigerant pressure is 200-3200 kPa (28.4-454.4 psi) with the ignition switch ON.
10-14 Volts | The ignition switch is ON.