GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Tracker - 4WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 HVAC Compressor Clutch Does Not Engage
Table 1: Compressor Control Module Voltage Table

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

1

Did you review the Air Delivery Description and Operation and 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 any position except the OFF position.
  3. Turn the A/C switch to the ON position.

Does the A/C compressor clutch engage?

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

Go to Step 3

3
  1. Exchange the compressor relay with a known good relay (the horn relay or the shiftlock relay).
  2. Start the engine.
  3. Turn the blower switch to any position except the OFF position.
  4. Turn the A/C switch to the ON position.

Does the A/C compressor clutch engage?

Go to Step 19

Go to Step 4

4
  1. Stop the engine.
  2. Disconnect the compressor clutch connector.
  3. Connect a test lamp between the compressor clutch connector and ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  4. Start the engine.
  5. Turn the blower switch to any position except the OFF position.
  6. Turn the A/C switch to the ON position.

Does the test lamp illuminate?

Go to Step 18

Go to Step 5

5

Test the compressor clutch supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 6

6

Test the compressor relay switch supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 7

7

Test the compressor relay coil supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 8

8

Test the compressor relay control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 9

9

Test the compressor control module supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 10

10

Test the compressor control module ground circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 11

11

Test the refrigerant pressure signal circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems and Pressure Cycling Switch Replacement .

Did you find and correct the condition?

Go to Step 28

Go to Step 12

12

Test the A/C request signal circuits (A/C and defrost switches) for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 13

13
  1. Depress the A/C switch.
  2. Test the A/C switch for a high resistance or for an open between terminals 2 and 3. Refer to Circuit Testing in Wiring Systems.

Did the switch test OK?

Go to Step 14

Go to Step 20

14
  1. Set the mode control to the defrost position.
  2. Test the defrost switch for a high resistance or for an open. Refer to Circuit Testing in Wiring Systems.

Did the switch test OK?

Go to Step 15

Go to Step 20

15

Test the A/C idle-up circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 16

16

Test the A/C cut-out circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 17

17
  1. Disconnect the evaporator temperature sensor connector.
  2. Measure the resistance of the evaporator temperature sensor.

    3. Evaporator Temperature Sensor Resistance
    1.8-2.2 kohms@25°C (77°F)

  3. 6.3-7.0 kohms@0°C (32°F)

Is the resistance within the specified range?

Go to Step 22

Go to Step 21

18

Inspect for a poor connection at the harness connector of the A/C compressor clutch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 23

19

Inspect for a poor connection at the harness connector of the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 24

20

Inspect for a poor connection at the harness connector of the A/C switch or the defrost switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 25

21

Inspect for a poor connection at the harness connector of the evaporator temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 26

22

Inspect for a poor connection at the harness connector of the A/C compressor control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 27

23

Replace the A/C compressor clutch. Refer to Air Conditioning Clutch Coil Replacement .

Did you complete the replacement?

Go to Step 28

--

24

Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement .

Did you complete the replacement?

Go to Step 28

--

25

Replace the A/C switch or the defrost switch. Refer to Control Assembly Replacement .

Did you complete the replacement?

Go to Step 28

--

26

Replace the evaporator temperature sensor. Refer to Evaporator Temperature Sensor Replacement .

Did you complete the replacement?

Go to Step 28

--

27

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 28

--

28

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3

Compressor Control Module Voltage Table

Terminal/Wire

Circuit

Normal Value

Condition

1-PNK

Compressor relay control

0-1 V

Blower switch ON and A/C or Defrost switch ON with engine running (Terminal 8 at more than 5 V)

10-14 V

Other than above with ignition switch ON

2-3

Not Used

4-YEL/BLK

A/C idle-up signal

10-14 V

Ignition switch ON, A/C switch or blower switch OFF

0-1 V

Ignition switch ON, A/C switch ON and blower switch ON

5-7

Not Used

8-GRN/YEL

A/C cutout signal

0-1.5 V

A/C not operating

10-14 V

A/C operating

9

Not Used

10-GRN/BLK

A/C request signal (A/C switch or Defrost switch)

0-1 V

Blower switch ON and A/C or Defrost switch ON with ignition switch ON

10-14 V

Blower switch OFF and A/C or Defrost switch OFF with ignition switch ON

11-12

Not Used

13-ORN

Refrigerant pressure switch signal

0-1 V

Ignition switch ON

14

Not Used

15-BLK

Ground

0-1 V

Ignition switch ON

16-BLK/WHT

Ignition positive voltage

10-14 V

Ignition switch ON

1-BLK/GRY

Evaporator temperature sensor ground

0-1 V

Ignition switch ON

2-BLK/GRY

Evaporator temperature sensor signal

0.9-1.1 V/1.8-2.2 kohms

Evaporator temperature 25°C (77°F) with ignition switch ON

2.2-2.4 V/6.3-7.0 kohms

Evaporator temperature 0°C (32°F) with ignition switch ON