HVAC

B1009-RECIRCULATION SWITCH REQUEST INPUT CIRCUIT/PERFORMANCE



Theory of Operation

The HVAC A/C Heater Control contains various switches and knobs that are used to change the systems operation. Many of the switches are momentary switches which are normally open or in the Off position and the status changes when the switch button or knob is pushed or turned. An active DTC indicates that the switch is stuck in an On position. A stored Diagnostic trouble Code (DTC) indicates that the switch was stuck in a On position for more than two minutes but has since returned to its normal state of Off.

- When Monitored:
With the ignition on.

- Set Condition:
If the Recirculation mode switch is stuck in a On position for more than two minutes. 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 Recirculation mode switch in an On position.

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

Is the Recirculation mode switch being held in or stuck On?

Yes

- Clean or repair the A/C Heater Control as necessary. If you are unable to clean the switch to where the switch can work properly, replace and program the A/C Heater Control.
- 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 two minutes.
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.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

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