Schematic Reference: HVAC Schematics

DEFINITION: Auxiliary air temperature can not be adjusted from one or both auxiliary controls or auxiliary cooling is insufficient.

1

Did you review the HVAC operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

Important: The auxiliary A/C system cannot request A/C compressor operation. The mode switch must be positioned to MAX, NORM, BI-LEVEL, BLEND or DEFROST on the HVAC control module to provide cooled airflow through the auxiliary system.

Does the HVAC control module operate and provide sufficient cooling?

Go to Step 3

Go to Too Hot in Vehicle

1. Turn ON the ignition, with the engine OFF.
2. Place the Heat and/or A/C auxiliary blower motor switch in each speed position.

Does the auxiliary blower motor operate at all?

Go to Step 4

Go to Auxiliary Blower Motor Inoperative

Does the auxiliary blower motor operate correctly for each speed position?

Go to Step 5

Go to Auxiliary Blower Motor Malfunction

Is the vehicle equipped with an auxiliary heating system?

Go to Step 6

Go to Step 7

6

1. Start engine.
2. Place the auxiliary heater blower motor switch in the OFF position.
3. Run the engine to achieve normal operating temperature.

Are the auxiliary heater hoses or auxiliary heater core hot?

Go to Step 8

Go to Step 7

7

Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test .

Did you find and correct the condition?

Go to Step 15

System OK

Disconnect the vacuum hose from the auxiliary coolant bypass valve.

Is there vacuum present at the auxiliary coolant bypass valve vacuum hose?

Go to Step 9

Go to Step 11

1. Turn OFF the ignition.
2. Disconnect the coolant bypass valve solenoid.
3. Connect a test lamp between the heater water control solenoid control circuit of the coolant bypass valve solenoid and a good ground.
4. Turn ON the ignition, with the engine OFF.
5. Place the auxiliary heater blower motor switch in the OFF position.

Does the test lamp illuminate?

Go to Step 10

Go to Step 11

Test the heater water control solenoid control circuit of the coolant bypass valve solenoid 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 15

Go to Step 12

Inspect for poor connections at the harness connector of the coolant bypass valve solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 13

Inspect for poor connections at the harness connector of the auxiliary heater blower motor switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 14

Replace the auxiliary coolant bypass valve. Refer to Heater Water Bypass Valve Replacement .

Did you complete the replacement?

Go to Step 15

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Replace the auxiliary heater blower motor switch. Refer to Heater Control Blower Switch Replacement .

Did you complete the replacement?

Go to Step 15

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2