Schematic Reference: HVAC Schematics

DEFINITION: Temperature can not be adjusted, or cooling 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

1. Turn ON the ignition, with the engine OFF.
2. Place the mode switch in any position except OFF.
3. Place the blower motor switch 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 the desired speed[s]?

--

Go to Step 4

Go to Blower Motor Malfunction

Turn the blower motor fan ON and select an air outlet mode.

Does air flow out of the selected HVAC outlet ducts.

--

Go to Step 5

Go to Air Delivery Improper

When A/C is ON, does the customer concern occur?

--

Go to Step 6

Go to Step 8

1. Start the engine.
2. Place the blower motor switch in the maximum speed position.
3. Place the mode switch in the BI-LEVEL position.
4. Place the air temperature switch in the coldest position.

Does the A/C compressor operate?

--

Go to Step 7

Go to HVAC Compressor Clutch Does Not Engage

7

Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 18

Go to Step  9

1. Observe the drive shaft of the air temperature actuator.
2. 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 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 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 11

Test the ground 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 12

Test the air temperature door control circuit of the air temperature actuator for an open, high resistance, short to ground, or 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 13

13

Important: Ensure that the HVAC control assembly 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 coldest position to the warmest position.

Does the voltage measure within the specified values with a smooth transition between COLD and HOT?

0-12 V

Go to Step 15

Go to Step 14

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 16

Inspect for poor connections at the harness connector of the HVAC control assembly. 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 assembly. Refer to Heater and Air Conditioning Control 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