Schematic Reference: HVAC Schematics

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 - Manual

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

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 4

Go to Auxiliary Blower Motor Inoperative

Does the auxiliary blower motor operate at the desired speed?

Go to Step 5

Go to Auxiliary Blower Motor Malfunction

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 6

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 17

Go to Step 7

1. Turn ON the ignition, with the engine OFF.
2. Place the front 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 8

Go to Step 14

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 9

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 10

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 12

Go to Step 11

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

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

Did you find and correct the condition?

Go to Step 17

Go to Step 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 17

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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 17

Go to Step 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 17

Go to Step 16

15

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

Did you complete the replacement?

Go to Step 17

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

Did you complete the replacement?

Go to Step 17

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2