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Too Cold in Vehicle



Too Cold in Vehicle

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






Circuit/System Description

The air temperature actuator is a 5-wire bi-directional electric motor that incorporate a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuators to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts.

Diagnostic Aids

Air Conditioning (A/C) System Performance Test

Observe the air delivery operation using the following operation:

1. Ignition ON, engine ON, blower motor switch in the MAX speed position
2. A/C switch in the ON position
3. Mode switch in the Panel or Bi-Level position
4. Press the recirculation switch, press the outside air switch

• Observe the recirculation door for proper movement to the Recirculation position. If the movement is not correct, refer to Air Delivery Improper Air Delivery Improper

Observe the following operation for proper A/C compressor operation:

1. Blower motor switch in the Max speed position
2. Mode switch in the Vent or Heater position
3. Temperature switch in the warmest position

If the A/C compressor still operates, refer to Air Conditioning Compressor Malfunction. Air Conditioning Compressor Malfunction

Observe the blower motor operation at various and desired speeds. If the speeds are not correct, refer to Blower Motor Malfunction. Blower Motor Malfunction

Inspect the air temperature door and the air temperature actuator for the following conditions:

* A misaligned air temperature actuator.
* Broken or binding linkages or air temperature door
* An obstruction that prevents the air temperature door from operating within its full range of motion
* Missing seals to the air temperature door
* Misaligned seals to the air temperature door
* Inspect the air temperature actuator, door, and any attaching linkage for binding or a condition that prevents drive shaft rotation

Inspect the cooling system for the following conditions:

* A low coolant level
* A loose or worn accessory belt
* A leaking radiator hose or heater hose
* A kinked radiator or heater hose
* A missing radiator cap pressure seal
* A leaking radiator cap
* Heating Performance Diagnostic

Circuit/System Verification

1. Turn ON the ignition, with the engine OFF.
2. Place the blower motor switch at the High speed position.
3. Place the mode switch in the Vent or Panel position.
4. Place the Air Temperature switch in the full COLD position.
5. Place the Air Temperature switch in the full HOT position.

The air temperature should change through the vent or panel.

Circuit/System Testing

1. Ignition OFF, disconnect the air temperature actuator harness connector at the air temperature actuator.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal E and ground.

• If greater than 1 ohm, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, test for 4.8 to 5.2 volts between the 5-volt reference circuit terminal C and ground.

• If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

• If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

4. Install a 3-amp fused jumper wire at the signal circuit terminal D, test for greater than 5 volts. Toggle the jumper wire between the low reference circuit terminal E and the 5-volt reference circuit terminal C.

• If the position signal parameter is less than 5 volts, test the signal circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

5. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit A terminal and B+.

• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test the B+ circuit of the HVAC control module for a short to ground, high resistance, or an open. If the circuit tests normal, test the HVAC control module ground circuit for a high resistance or an open. If the circuit tests normal, replace the HVAC control module.

6. Ignition OFF, verify that a test lamp does not illuminate between control circuit terminal A terminal and B+.

• If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal replace the HVAC control module.

7. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit B terminal and B+.

• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test the B+ circuit of the HVAC control module for a short to ground, high resistance, or an open. If the circuit tests normal, test the HVAC control module ground circuit for a high resistance or an open. If the circuit tests normal, replace the HVAC control module.

8. Ignition OFF, verify that the test lamp does not illuminate between control circuit terminal B and B+.

• If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal replace the HVAC control module.

9. If all circuits test normal, replace the air temperature actuator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Refer to Programming and Relearning for ECM replacement, setup, and programming
* Air Temperature Actuator Replacement
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