B1012

B1012-92-DEFROST MODE SWITCH REQUEST INPUT - PERFORMANCE OR INCORRECT OPERATION

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

Theory of Operation

The HVAC A/C Heater Control contains various switches and knobs that are used to change the systems operation. There are currently three types of switches used depending on the configuration of the system. Push button momentary switches which are normally open or in the Off position. Multifunction or rotary switches which have several distinct positions and potentiometers which are a rotary variable resistor that is used for a more precise control. An active Diagnostic Trouble Code (DTC) indicates that either a control switch or potentiometer is stuck in an On position or out of a calibrated range. A stored DTC indicates that control switch or potentiometer was stuck On or out of calibration but has since returned to its normal state. For further information Description and Operation.

- When Monitored:
With the ignition on.

- Set Condition:
If the Defrost Mode Control Switch is stuck in an On position for more than 30 seconds. This DTC has a de-maturing time of one second. If the DTCs status changes from active to stored, the DTC will stay in memory for 100 ignition cycles.





Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. HVAC Pre-Diagnostic Troubleshooting Procedure.

1. INSPECT FOR OBJECT HOLDING SWITCH IN AN ON POSITION
1. Inspect the A/C Heater Control for an object or debris holding the Defrost Mode Control Switch in an On position.

NOTE: Using the scan tool you can read the On/Off status of the control switch.

Is the Defrost Mode Control Switch being held in or stuck On?

Yes

- The A/C Heater control cannot be repaired or adjusted and must be replaced if inoperative or damaged but it might be cleanable if external debris is inhibiting the proper operation of the control switch or knob. If you are unable to clean the control to where it can function properly, replace and program the A/C Heater Control. A/C And Heater Control - Removal.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 2

2. A/C HEATER CONTROL
1. Turn the ignition on.
2. Using the scan tool, erase HVAC DTCs.
3. Turn the ignition off for 10 seconds, and then turn the ignition on and wait a minimum of 30 seconds.
4. Using the scan tool, read HVAC DTCs.

Does the scan tool display this DTC as Active or is the status of the switch reading On?

Yes

- Replace and program the A/C Heater Control. A/C And Heater Control - Removal.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Test complete.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.