No Response From HVAC (A/C Heater Control Module)

NO RESPONSE FROM HVAC (HEAT VENTILATION AND A/C)





For a complete wiring diagram, refer to the Wiring Information.






1. TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.

NOTE: Make sure the IOD fuse is installed and battery voltage is between 10.0 and 16.0 volts.

2. Using the scan tool, select ECU View.

NOTE: A red "X" will be next to the module that is not communicating, indicating that the module is not active on the Bus network. A green check indicates that the module is active on the Bus network.

Does the scan tool display a red "X" next to the module?

Yes

- Go To 2

No

- The no response condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched and partially broken wires and the wiring harness connectors for broken, bent, pushed out and corroded terminals.

2. (F500) FUSED RUN RELAY OUTPUT CIRCUIT OPEN OR SHORTED




1. Turn the ignition off.
2. Disconnect the A/C Heater Control C1 harness connector.
3. Using a 12-volt test light connected to ground, check the (F500) Fused Run Relay Output circuit.

Does the test light illuminate brightly?

Yes

- Go To 3

No

- Repair the (F500) Fused Run Relay Output circuit for an open or short.
- Perform the BODY VERIFICATION TEST. Body Verification Test

3. (Z909) GROUND CIRCUIT OPEN




1. Using a 12-volt test light connected to 12-volts, check the (Z909) ground circuit.

Does the test light illuminate brightly?

Yes

- Go To 4

No

- Repair the (Z909) ground circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test

4. (D55) AND (D54) CAN B BUS CIRCUITS OPEN





NOTE: One open circuit will not cause this condition.

1. Measure the voltage between the (D54) CAN B Bus (-) circuit and ground.
2. Measure the voltage between the (D55) CAN B Bus (+) circuit and ground.

Is there any voltage present on either circuit?

Yes

- Replace the A/C Heater Control.
- Perform the BODY VERIFICATION TEST. Body Verification Test

No

- Repair the (D55) and (D54) CAN B Bus circuits for an open. Inspect the connector for damage.
- Perform the BODY VERIFICATION TEST. Body Verification Test