B1185

B1185-LEFT TEMP DOWN 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 DTC indicates that the switch was stuck in a On position for more than 60 seconds but has since returned to its normal state of Off.

- When Monitored:
With the ignition on.

- Set Condition:
If the Left Temperature Down Control Switch is stuck in an On position for more than 60 seconds. This DTC has a de-maturing time of two seconds. 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. Initial Inspection and Diagnostic Overview.

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

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

Is the Left Temperature Down Control 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 HVAC VERIFICATION TEST HVAC Verification Test.

No

- Go To 2

2. A/C HEATER CONTROL
1. Turn the ignition on.
2. With 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 60 seconds.
4. With 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 HVAC VERIFICATION TEST HVAC Verification Test.

No

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