GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 Envoy XUV 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Too Cold in Vehicle - Auxiliary

Too Cold in Vehicle - Auxiliary VIN 3 including Envoy XUV

Diagnostic Aids

The air temperature for the flow through console is regulated by the air temperature actuator for the primary HVAC system. Ensure the primary HVAC system is functioning properly.

Test Description

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

  1. This test resets HVAC control module and checks for current air temperature actuator DTC.

    2.

  2. This checks for proper airflow for each auxiliary blower motor speed position.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The auxiliary heating is insufficient.

1

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Recalibrate actuators. Refer to Actuator Recalibration .
  2. With a scan tool, observe the Heating and Air Conditioning DTC List.

Does DTC B0229, B0414, B0424, B3761 or B3770 set?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch in each speed position.

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

Go to Step 4

Go to Auxiliary Blower Motor Inoperative

4

Does the auxiliary blower motor operate at the desired speed?

Go to Too Cold in Vehicle

Go to Auxiliary Blower Motor Malfunction

Too Cold in Vehicle - Auxiliary VIN 6 excluding Envoy XUV

Test Description

The number below refers to the step number in the diagnostic table.

  1. The primary HVAC control module controls the coolant bypass valve. It receives a Class 2 message from the auxiliary HVAC control module for the proper position of valve.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

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

1

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2
  1. Recalibrate actuators. Refer to Actuator Recalibration .
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the DTC list in Rear HVAC/RSA.

Does the scan tool display DTC B0145, B0428, or B3531?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3
  1. With a scan tool, observe the Rear Temp. Select Sw. parameter in the Rear HVAC/RSA data list.
  2. Press the auxiliary temperature switch UP and DOWN

Does the scan tool indicate the Rear Temp. Select Sw. parameter change with each command?

Go to Step 4

Go to Step 15

4
  1. Turn ON the ignition, with the engine OFF.
  2. Place the auxiliary blower motor switch in each speed position.

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

Go to Step 5

Go to Auxiliary Blower Motor Inoperative

5

Does the auxiliary blower motor operate at the desired speed?

Go to Step 6

Go to Auxiliary Blower Motor Malfunction

6
  1. Start the engine.
  2. Place the mode switch in the Panel 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

Perform the Heating Performance Diagnostic. 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 9

8
  1. Turn ON the ignition, with the engine OFF.
  2. Place the auxiliary blower motor switch in the Rear position.
  3. With a scan tool, observe the Air Mix Door Actual parameter in the Rear HVAC/RSA data list.
  4. Place the auxiliary air temperature switch from the coldest position to the warmest position.

Does the Air Mix Door Actual parameter counts change?

Go to Step 9

Go to Step 15

9
  1. Turn ON the ignition, with the engine OFF.
  2. Place the auxiliary air temperature switch to the warmest position.
  3. Start the engine.
  4. Allow the engine to reach its normal operating temperature.
  5. Feel the inlet and outlet hoses of the coolant bypass valve.

Does the inlet hose feel as warm as the outlet hose of the coolant bypass valve?

System OK

Go to Step 10

10
  1. Turn OFF the engine.
  2. Disconnect the electrical connector of the coolant bypass valve.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the coolant bypass solenoid control circuit and the ground circuit of the coolant bypass valve.
  5. With a scan tool, command the Water Valve ON and OFF.

Does the test lamp illuminate with each command?

Go to Vacuum Control System Diagnostic

Go to Step 11

11
  1. Connect a test lamp between the coolant bypass solenoid control circuit of the coolant bypass valve and a good ground.
  2. With a scan tool, command the Water Valve ON and OFF.

Does the test lamp illuminate with each command?

Go to Step 13

Go to Step 12

12

Test the coolant bypass solenoid control circuit of the coolant bypass valve for one of the following conditions:

    • A short to ground
    • A high resistance
    • An open

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 14

13

Repair the ground circuit of the coolant bypass valve. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 18

--

14

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 16

15

Inspect for poor connections at the harness connector of the auxiliary 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 HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

Go to Step 18

--

17

Replace the auxiliary HVAC control module. Refer to Auxiliary Heater and Air Conditioning 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