Diagnostic Aids
If vehicle is equipped with K08 Coolant Heater also known as Fuel Operated Heater and Auxiliary Heater option, be sure to check for trouble codes in the scan tool under Powertrain, Auxiliary Heater Control Module.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This checks for proper cooling system operation.
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The voltage will vary between 0-12 volts during normal operation. The HVAC control assembly connector must be connected during this step.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Temperature cannot be adjusted or the heating is insufficient. | ||||||||||||||||
1 | Did you review the HVAC operation and perform the necessary inspections? | -- | Go to Step 2 | |||||||||||||
2 |
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 correctly for each speed position? | -- | Go to Step 4 | Go to Blower Motor Malfunction | ||||||||||||
4 |
Does air flow out of the selected HVAC outlet ducts? | -- | Go to Step 5 | Go to Air Delivery Improper | ||||||||||||
Inspect the cooling system for the following:
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 6 | |||||||||||||
6 |
Does the A/C compressor operate? | -- | Go to Step 7 | |||||||||||||
7 |
Does the air temperature actuator drive shaft rotate at all? | -- | Go to Step 8 | Go to Step 9 | ||||||||||||
8 | Inspect the air temperature door and the air temperature actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 9 | ||||||||||||
9 | Test the ignition 3 voltage circuit of the air temperature actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 10 | ||||||||||||
10 | Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 11 | ||||||||||||
11 | Test the air temperature door control circuit of the air temperature actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 12 | ||||||||||||
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Important:: Ensure that the HVAC control assembly connector is connected during this step in order to avoid misdiagnosis.
Does the voltage measure within the specified values with a smooth transition between COLD and HOT? | 0-12 V | Go to Step 13 | Go to Step 14 | |||||||||||||
13 | 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 17 | Go to Step 15 | ||||||||||||
14 | Inspect for poor connections at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | ||||||||||||
15 | Replace the air temperature actuator. Refer to Temperature Valve Actuator Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||||||||
16 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||||||||
17 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 | ||||||||||||
