GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Rendezvous - FWD 🢒 HVAC 🢒 HVAC - Manual 🢒 Too Cold in Vehicle

Test Description

The number below refers to the step number 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

Connector End View Reference: HVAC Connector End Views

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

1

Important: The single C60 HVAC Manual air temperature control and the dual CJ3 HVAC Manual control is diagnosed in this table.

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

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 in each speed position?

--

Go to Step 4

Go to Blower Motor Malfunction

4

Except for the blower motor speed, are all of the functions of the HVAC control module inoperative?

--

Go to Step 13

Go to Step 5

5

Inspect the cooling system for the following conditions:

    • A low coolant level
    • A loose or worn accessory drive belt
    • A leaking radiator hose or heater hoses
    • A kinked radiator hose or heater hoses
    • A missing radiator cap pressure seal
    • A leaking radiator cap

Did you find and correct the condition?

--

Go to Step 22

Go to Step 6

6
  1. Start the engine.
  2. Place the blower switch in the OFF position.
  3. Place the A/C request switch in the OFF position.

Does the A/C compressor operate?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 7

7
  1. Observe the drive shaft to the air temperature actuator or actuators.
  2. Adjust the air temperature switch.

Does the drive shaft of the air temperature actuator or actuators rotate?

--

Go to Step 8

Go to Step 9

8

Inspect the air temperature door of the air temperature actuator or actuators for the following conditions:

    • Broken or binding linkages of the air temperature door or doors
    • An obstruction that prevents the air temperature door or doors from operating within the full range of motion
    • Missing seals to the air temperature door or doors
    • Misaligned seals to the air temperature door or doors

Did you find and correct the condition?

--

Go to Step 22

Go to Heating Performance Diagnostic

9

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

Did you find and correct the condition?

--

Go to Step 22

Go to Step 10

10

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

Did you find and correct the condition?

--

Go to Step 22

Go to Step 11

11

Test the door control circuit of the suspect air temperature actuator or actuators for an open, a high resistance, a short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

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 door control circuit of the air temperature actuator or actuators to a good ground.
  3. Place the air temperature switch from the coldest position to the warmest position.

Is the voltage measurement within the specified values with a smooth transition between cold and hot?

0 V at cold

12 V at hot

Go to Step 17

Go to Step 19

13

Test the ignition 3 voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 14

14

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

Did you find and correct the condition?

--

Go to Step 22

Go to Step 15

15

Test the blower motor control OFF circuit of the HVAC control module for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 16

16

Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 19

17

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 .

Did you find and correct the condition?

Go to Step 22

Go to Step 18

18

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 22

Go to Step 20

19

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 .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 21

20

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

Did you complete the replacement?

--

Go to Step 22

--

21

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

Did you complete the replacement?

--

Go to Step 22

--

22

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2