Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The temperature cannot be adjusted, or the heating is insufficient.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

1. Turn ON the ignition, with the engine OFF.
2. Place the blower control in each speed position.

Does the blower motor operate in any of the speed positions?

--

Go to Step 3

Go to Blower Motor Inoperative

Does the blower motor operate in each speed position?

--

Go to Step 4

Go to Blower Motor Malfunction

1. Start the engine.
2. Turn OFF the HVAC controls.

Does the A/C compressor clutch engage?

--

Go to HVAC Compressor Clutch Does Not Disengage

Go to Step 5

Inspect the cooling system for the following conditions:

Did you find and correct the condition?

--

Go to Step 18

Go to Step 6

Perform the Heating Performance Diagnostic. Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 7

1. Turn ON the ignition, with the engine OFF.
2. Observe the drive shaft of the air temperature actuator.
3. Place the air temperature switch from the coldest position to the warmest position.

Does the air temperature actuator drive shaft rotate at all?

--

Go to Step 8

Go to Step 9

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

Did you find and correct the condition?

--

Go to Step 18

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 10

Test the low reference circuit of the air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 11

Test the air temperature door control circuit of the air temperature actuator for an open, a high resistance, a short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 12

Important:: Ensure that the HVAC control module connector is connected during this step in order to avoid misdiagnosis.

1. Turn ON the ignition, with the engine OFF.
2. Measure the voltage from the air temperature door control circuit of the air temperature actuator to a good ground.
3. Place the air temperature switch from the coldest position to the warmest position.

Is the voltage within the specified values with a smooth transition between cold and hot?

0 V at cold 12 V at hot

Go to Step 13

Go to Step 15

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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 14

Inspect the air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement .

Did you complete the replacement?

--

Go to Step 18

--

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 18

--

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2