Schematic Reference: HVAC Schematics

DEFINITION: The auxiliary temperature cannot be adjusted, or the auxiliary cooling is insufficient during A/C operation.

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

Does the customer concern occur when the A/C is OFF?

Go to Step 8

Go to Step 6

6

IMPORTANT:: Ambient air temperature must be above 3°C (36°F).

1. Start the engine.
2. Place the blower motor switch in the maximum speed position.
3. Place the A/C request switch in the ON position.
4. Place the left air temperature switch in the coldest position.

Does the A/C compressor operate?

Go to Step 7

Go to HVAC Compressor Clutch Does Not Engage

Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

Go to Step 20

Go to Step  8

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 9

Go to Step 18

1. Turn ON the ignition, with the engine OFF.
2. Place the auxiliary air temperature switch to the coldest 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 warmer than 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 on and off with each command?

Go to Vacuum Control System Diagnostic

Go to Step 11

Does the test lamp remain illuminated when commanded to OFF?

Go to Step 14

Go to Step 12

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 15

Go to Step 13

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

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

Did you find and correct the condition?

Go to Step 20

Go to Step 16

Test the coolant bypass solenoid control circuit of the coolant bypass valve for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 17

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

Did you complete the repair?

Go to Step 20

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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 20

Go to Step 18

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 20

Go to Step 19

18

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

Did you complete the replacement?

Go to Step 20

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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 20

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2