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 no condition is found with all conditions listed, then compare door travel to a known good vehicle.
Step | Action | Values | Yes | No | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics DEFINITION: The 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 operate in any of the speed positions? | -- | Go to Step 3 | Go to Blower Motor Malfunction | ||||||||||||
3 | Does the blower actuator operate correctly for each speed position? | -- | Go to Step 4 | Go to Blower Motor Malfunction | ||||||||||||
Is the HVAC control assembly inoperative? | -- | Go to Step 17 | Go to Step 5 | |||||||||||||
5 | Inspect the cooling system for the following:
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 6 | ||||||||||||
6 |
Does the A/C compressor operate? | -- | Go to Step 7 | |||||||||||||
7 |
Does the drive shaft of both air temperature actuators rotate? | -- | Go to Step 8 | Go to Step 9 | ||||||||||||
Inspect the appropriate air temperature door and the appropriate air temperature door actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 21 | ||||||||||||||
9 | Test the position signal circuit of the appropriate temperature actuator for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 10 | ||||||||||||
10 | Test the low reference circuit of the appropriate temperature actuator for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 11 | ||||||||||||
11 | Test the 5-volt reference circuit of the appropriate air temperature actuator for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 12 | ||||||||||||
12 |
Does the test lamp illuminate in both positions? | -- | Go to Step 21 | Go to Step 13 | ||||||||||||
13 | Test the temperature door control A and temperature door control B circuits of the appropriate temperature actuator for an open, a high resistance, a short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 14 | ||||||||||||
14 | Test the ignition 3 voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 17 | ||||||||||||
15 | Test the ground circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 18 | |||||||||||||
16 | Inspect the appropriate air temperature door for a mechanical condition or for a condition that allows excessive travel of the door. Did you complete the repair? | -- | Go to Step 21 | -- | ||||||||||||
17 | Inspect for poor connections at the harness connector of the appropriate 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 21 | Go to Step 19 | ||||||||||||
18 | 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 . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 | ||||||||||||
19 |
Important: Perform the calibration procedure for the air temperature actuator. Replace the appropriate air temperature door actuator. Refer to Temperature Valve Actuator Replacement - Right Side Temperature Valve Actuator Replacement - Left Side . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||||
20 | Replace the HVAC control module. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||||
21 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |