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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2001 🢒 Regal (China) 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Too Cold in Vehicle

Too Cold in Vehicle CJ3

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The voltage will vary between 0-12 volts during normal operation. The HVAC control module connector must be connected during this step.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: The temperature cannot be adjusted, or the heating is insufficient.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower control in each speed position.

Does the blower motor operate in any of the speed positions?

--

Go to Step 3

Go to Blower Motor Inoperative

3

Does the blower motor operate at the desired speeds?

--

Go to Step 4

Go to Blower Motor Malfunction

4

Inspect the cooling system for the following conditions:

  1. A low coolant level
  2. A loose or a worn accessory drive belt
  3. A leaking radiator hose or heater hose
  4. A kinked radiator hose or heater hose
  5. A missing radiator cap pressure seal
  6. A leaking radiator cap

Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 5

5
  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Place the mode switch in the MAX position.

Does the recirculation door move to the recirculation position?

--

Go to Step 6

Go to Air Delivery Improper

6

Place the mode switch in the VENT or HTR positions

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 7

7
  1. Observe the left and right air temperature actuator drive shaft.
  2. Place the air temperature switch from the coldest position to the warmest position.

Does the left and right air temperature actuator drive shaft rotate at all?

--

Go to Step 8

Go to Step 9

8

Inspect the left and right air temperature door and the left and right air temperature actuator for the following conditions:

    • An incorrectly installed air temperature actuator. Refer to Air Temperature Actuator Replacement - Left Side and Air Temperature Actuator Replacement - Right Side .
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within it's full range of motion.
    • Missing seals to the air temperature door
    • Misaligned seals to the air temperature door

Did you find and correct the condition?

--

Go to Step 18

Go to Step 9

9

Test the ignition-3 voltage circuit of the suspect air temperature actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs a in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 10

10

Test the ground circuit of the suspect air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 11

11

Test the suspect air temperature door position signal circuit of the air temperature actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 12

12

Important: Ensure that the HVAC control module connector is connected during this step in order to avoid misdiagnosis.

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the suspect air temperature door position signal circuit of the suspect air temperature actuator to a good ground.
  3. Place the air temperature switch from the coldest position to the warmest position.

Does the voltage measure within the specified values with a smooth transition between cold and hot?

0-12 V

Go to Step 15

Go to Step 13

13

Inspect for poor connections at the harness connector of the suspect air temperature actuator. 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 18

Go to Step 14

14

Inspect the suspect air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

15

Inspect for poor connections at the harness connector of the HVAC 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 18

Go to Step 17

16

Replace the suspect air temperature actuator. Refer to Air Temperature Actuator Replacement - Left Side or Air Temperature Actuator Replacement - Right Side .

Did you complete the replacement?

--

Go to Step 18

--

17

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2

Too Cold in Vehicle CJ4

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The voltage will vary between 0-12 volts during normal operation. The HVAC control module connector must be connected during this step.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: The temperature cannot be adjusted, or the heating is insufficient.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch in each speed position.

Does the blower motor operate in any of the speed positions?

--

Go to Step 3

Go to Blower Motor Inoperative

3

Does the blower motor operate at the desired speeds?

--

Go to Step 4

Go to Blower Motor Malfunction

4

Inspect the cooling system for the following conditions:

  1. A low coolant level
  2. A loose or worn accessory drive belt
  3. A leaking radiator hose or heater hose
  4. A kinked radiator hose or heater hose
  5. A missing radiator cap pressure seal
  6. A leaking radiator cap

Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 5

5
  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Place the recirculation switch in the recirculation position.

Does the recirculation door move to the recirculation position?

--

Go to Step 6

Go to Air Recirculation Malfunction

6

Place the A/C switch in the OFF.

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 7

7
  1. Observe the drive shaft of the air temperature actuator.
  2. Place the air temperature switch from the coldest position to the warmest position.

Does the air temperature actuator drive shaft rotate at all?

--

Go to Step 8

Go to Step 9

8

Inspect the air temperature door and the air temperature actuator for the following conditions:

    • A misaligned air temperature actuator. Refer to Air Temperature Actuator Replacement .
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within it's full range of motion
    • Missing seals to the air temperature door
    • Misaligned seals to the air temperature door

Did you find and correct the condition?

--

Go to Step 23

Go to Step 13

9

Test the ignition-3 voltage circuit of the air temperature actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 10

10

Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 11

11

Test the air temperature door position signal circuit of the air temperature actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 12

12

Important: Ensure that the HVAC control module connector is connected during this step in order to avoid misdiagnosis.

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the air temperature door position signal circuit of the air temperature actuator to a good ground.
  3. Place the air temperature switch from the coldest position to the warmest position.

Does the voltage measure within the specified values with a smooth transition between cold and hot?

0-12 V

Go to Step 19

Go to Step 20

13
  1. Disconnect the HVAC control module .
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the voltage from the ignition-3 voltage circuit of the HVAC control module to the ground circuit of the HVAC control module .

Does the voltage measure greater than specified value?

12 V

Go to Step 15

Go to Step 14

14

Measure the voltage from the ignition-3 voltage circuit of the HVAC control module to a good ground.

Does the voltage measure greater than specified value?

12 V

Go to Step 16

Go to Step 17

15

Measure the voltage from the battery positive voltage circuit of the HVAC control module to a good ground.

Does the voltage measure greater than specified value?

12 V

Go to Step 20

Go to Step 18

16

Test the ground circuit of the HVAC control module for short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 20

17

Test the ignition-3 circuit of the HVAC control module for short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 20

18

Test the battery positive voltage circuit of the HVAC control module for short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 20

19

Inspect for poor connections at the harness connector of the air temperature actuator. 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 23

Go to Step 21

20

Inspect for poor connections at the harness connector of the HVAC 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 23

Go to Step 22

21

Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement .

Did you complete the replacement?

--

Go to Step 23

--

22

Replace the HVAC control module . Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 23

--

23

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2