Why does the rear A/C blow hot and the front cold if the hardline is cold all the way back? What do I need to replace?
Jul 24, 2023 at 7:10 PM
Rear A/C not working?
2013 CHEVROLET TAHOE
MATTYU86
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Hello MATTYU86,
It may be something called a blend door or blend door actuator. It is the diverter door within the system for directing air through the evaporator and/or heater core. If it is stuck in the heat position it will just blow hot air.
It may also be an Air Temperature Sensor.
Does this vehicle have Automatic Temperature Controls?
Does everything up front work as it should?
There is a re-calibration procedure for these doors. Let's try it and see if we can get it to reset.
Do you have a scan tool or code reader? If so, did you find any codes?
If you do not have one, you can go to AutoZone or other auto parts stores and they will scan it for free.
Write down any codes that are found. Paying special attention to codes that begin with B or U.
Once you have these codes have them clear them all. This will need to be done in order to start the calibration process.
Once done you can use this method:
1) Turn the key to the off position.
2) If anything has been disconnected, please plug everything back in.
3) Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
4) Install the HVAC/ECAS fuse.
5) Wait about 40 seconds for the HVAC control module to self-calibrate.
6) verify no Diagnostic Trouble Codes have been set as "Current".
I have added a diagram of the fuse box showing the location of this fuse. It should be fuse 39 10-amp red. (See image)
Thank you,
Brendon
It may be something called a blend door or blend door actuator. It is the diverter door within the system for directing air through the evaporator and/or heater core. If it is stuck in the heat position it will just blow hot air.
It may also be an Air Temperature Sensor.
Does this vehicle have Automatic Temperature Controls?
Does everything up front work as it should?
There is a re-calibration procedure for these doors. Let's try it and see if we can get it to reset.
Do you have a scan tool or code reader? If so, did you find any codes?
If you do not have one, you can go to AutoZone or other auto parts stores and they will scan it for free.
Write down any codes that are found. Paying special attention to codes that begin with B or U.
Once you have these codes have them clear them all. This will need to be done in order to start the calibration process.
Once done you can use this method:
1) Turn the key to the off position.
2) If anything has been disconnected, please plug everything back in.
3) Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
4) Install the HVAC/ECAS fuse.
5) Wait about 40 seconds for the HVAC control module to self-calibrate.
6) verify no Diagnostic Trouble Codes have been set as "Current".
I have added a diagram of the fuse box showing the location of this fuse. It should be fuse 39 10-amp red. (See image)
Thank you,
Brendon
Image (Click to enlarge)
Jul 25, 2023 at 4:51 PM
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