For 1990-2009 cars

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference : HVAC Schematics DEFINITION: The temperature cannot be adjusted, or the cooling is insufficient during A/C operation.
1 | Did you review the HVAC operation and perform the necessary inspections? | -- | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual
2 | Does the blower motor operate correctly for each speed position? | -- | Go to Step 3 | Go to Blower Motor Malfunction
3 | Is the HVAC control assembly inoperative? | -- | Go to Step 14 | Go to Step 4
4 | Does the Too Hot in Vehicle concern occur when A/C cooling is desired? | -- | Go to Step 5 | Go to Step 7
5 | Important: For A/C compressor operation, the ambient air temperature must be above 3°C (38°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 air temperature switch in the coldest position.

Does the A/C compressor operate?

--

Go to Step 6

Go to Air Conditioning Compressor Malfunction

6 | 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 21 | Go to Step 7
7 |

1. Observe the drive shaft of both air temperature actuators.
2. Adjust the air temperature switch.

Does the drive shaft of both air temperature actuators rotate?

--

Go to Step 8

Go to Step 9

8 | Inspect the appropriate air temperature door and the appropriate air temperature actuator for the following conditions:

• | A misaligned air temperature actuator.

• | Broken linkages or binding linkages

• | A broken air temperature door or a binding air temperature door.

• | An obstruction that prevents the air temperature door from operating within the full range of motion.

• | Missing seals to the air temperature door

• | Misaligned seals to the air temperature door.

Did you find and correct the condition?

--

Go to Step 21

Go to Testing for Intermittent Conditions and Poor Connections

9 | Test the position signal circuit of the appropriate 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 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 to 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 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 21 | Go to Step 12
12 |

1. Turn OFF the ignition.
2. Reconnect the appropriate temperature actuator.
3. Turn ON the ignition with the engine OFF.
4. Connect a test lamp between temperature door control A and temperature door control B circuits of the appropriate temperature actuator connector.
5. Place the temperature switch in the cold position.
6. Place the mode switch in the hot position.

Does the test lamp illuminate in both positions?

--

Go to Step 16

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 to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18
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 to Wiring Repairs . Did you find and correct the condition? |  | Go to Step 21 | Go to Step 15
15 | Test the ground circuit of the HVAC control module 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 21 | --
16 | Inspect for poor connections at the harness connector of the appropriate 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 21 | Go to Step 17
17 | Inspect the appropriate 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 21 | Go to Step 19
18 | 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 21 | Go to Step 20
19 | Important: Perform the calibration procedure for the air temperature actuator. Replace the appropriate air temperature 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 | 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 21 | --
21 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2