Heating & AC System: 81

81-BLOWER NOT ON HIGH AT START OF COOLDOWN TEST







- When Monitored:
When executing the Cooldown Test.

- Set Condition:
If the A/C Heater Control sensed that the blower was not operating at high speed when executing the Cooldown Test.





NOTE: This DTC will display as active if the ignition is not cycled after running the Cool down Test. Otherwise, it will display as stored until cleared.

1. CHECK THE BLOWER SPEED SETTING

Was the blower control set to high speed before executing the Cooldown Test?

Yes

- Go To 2

No

- Start the engine, set the blower control to high speed, and then run the Cooldown Test again.
- Perform the BODY VERIFICATION TEST Body Verification Test.

2. CHECK THE (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO THE (C121) SENSOR GROUND CIRCUIT




1. Turn the ignition off.
2. Disconnect the A/C Heater Control C2 harness connector.
3. Measure the resistance between the (C41) Blower Switch Position Signal circuit and the (C121) Sensor Ground circuit in the A/C Heater Control C2 harness connector.

Is the resistance below 10K ohms?

Yes

- Repair the (C41) Blower Switch Position Signal circuit for a short to the (C121) Sensor Ground circuit. Run the Cooldown Test again after the repair is complete.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 3

3. CHECK THE (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT VOLTAGE




1. Reconnect the A/C Heater Control C2 harness connector.
2. Disconnect the A/C Heater Control C3 harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (C41) Blower Switch Position Signal circuit.

Is the voltage above 4.8 volts?

Yes

- Check the blower motor and related circuits for the cause of blower operation problems and repair as necessary. Run the Cooldown Test again after the repair is complete.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 4

4. CHECK THE (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Turn the ignition off.
2. Disconnect the A/C Heater Control C2 harness connector.
3. Measure the resistance of the (C41) Blower Switch Position Signal circuit between ground and the A/C Heater Control C3 harness connector.

Is the resistance below 10K ohms?

Yes

- Repair the (C41) Blower Switch Position Signal circuit for a short to ground. Run the Cooldown Test again after the repair is complete.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 5

5. CHECK (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR AN OPEN




1. Measure the resistance of the (C41) Blower Switch Position Signal circuit between the A/C Heater Control C2 harness connector and the A/C Heater Control C3 harness connector.

Is the resistance below 5.0 ohms?

Yes

- Replace the A/C Heater Control. Run the Cooldown Test again after the repair is complete.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Repair the (C41) Blower Switch Position Signal circuit for an open. Run the Cooldown Test again after the repair is complete.
- Perform the BODY VERIFICATION TEST Body Verification Test.