The numbers below refer to the step numbers on the diagnostic table.
The HVAC control module is inoperative when the module does not respond to an operator control request.
If the condition does not occur when an air conditioning (A/C) request has been made then you must bypass the A/C performance test procedures.
These actions are the enable criteria for the A/C compressor to operate. Ambient air temperature must be above 3°C (38°F) in order for this A/C compressor test to be run.
Performing the Air Conditioning System Performance Test ensures that the A/C system is operating properly for further testing.
If no condition found with all conditions listed then compare door travel to known good vehicle.
The voltage will vary between 0-5 volts during normal operation. Ensure to observe the air temperature actuator driveshaft and the volt meter when jumping the control circuit with 5-volt reference and the ground circuits. The air temperature actuator and the HVAC control assembly connectors must be connected during this step.
Step | Action | Values | Yes | No | ||||||||||||
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Schematic Reference: HVAC Schematics DEFINITION: The temperature cannot be adjusted, or the cooling is insufficient during A/C operation. | ||||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||||
2 |
Does the blower motor operate at all? | -- | 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 | ||||||||||||
Is the HVAC control assembly inoperative? | -- | Go to Step 18 | Go to Step 5 | |||||||||||||
Does the Too Hot in Vehicle concern occur when air conditioning (A/C) cooling is desired? | -- | Go to Step 6 | Go to Step 8 | |||||||||||||
Important: For A/C compressor operation, the ambient air temperature must be above 3°C (38°F).
Does the A/C compressor operate? | -- | Go to Step 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 25 | Go to Step 8 | |||||||||||||
8 |
Does the drive shaft of the air temperature actuator ever rotate? | -- | Go to Step 9 | Go to Step 10 | ||||||||||||
Inspect the air temperature door and the air temperature actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 25 | Go to Testing for Intermittent Conditions and Poor Connections | |||||||||||||
10 | Test the ignition 1 voltage circuit of the air temperature actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 11 | ||||||||||||
11 | Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 12 | ||||||||||||
12 | Test the 5-volt reference circuit of the air temperature actuator for a high resistance. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 13 | ||||||||||||
13 | Test the signal circuit of the air temperature door actuator for an open or a high resistance. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 14 | ||||||||||||
14 | Test the door control circuit of the air temperature actuator an open or a high resistance. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 15 | ||||||||||||
Important: Ensure the air temperature actuator connector and the HVAC control assembly connectors are connected during this step to avoid misdiagnosis.
Does the drive shaft of the air temperature actuator rotate and does the voltage change? | -- | Go to Step 16 | Go to Step 20 | |||||||||||||
16 |
Important:: Ensure the air temperature actuator connector is connected during this step to avoid misdiagnosis.
Is the voltage measurement near the specified value in each condition? | 0 V increasing 5 V decreasing 2.5 V stationary | Go to Step 17 | Go to Step 22 | ||||||||||||
17 | Inspect the air temperature door for a mechanical condition or for a condition that allows excessive travel of the door. Did you find and correct the condition? | -- | Go to Step 25 | -- | ||||||||||||
18 | Test the ignition 1 voltage circuit of the HVAC control assembly for the following:
Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 19 | ||||||||||||
19 | Test the ground circuit of the HVAC control assembly for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 22 | ||||||||||||
20 | Inspect for poor connections at the harness connector of the air temperature actuator. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 21 | ||||||||||||
21 | Inspect the air temperature actuator, the door, and any attaching linkage for binding or for a condition that prevents drive shaft rotation. Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 23 | ||||||||||||
22 | Inspect for poor connections at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | -- | Go to Step 25 | Go to Step 24 | ||||||||||||
23 |
Important: Perform the calibration procedure for the air temperature actuator. Replace the air temperature actuator. Refer to Temperature Valve Actuator Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||||||
24 |
Important: Perform the calibration procedure for the HVAC control assembly. Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 25 | -- | ||||||||||||
25 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |