Issue with temperature and defrost

[danielspivey]

I know many have discussed issues w the HVAC in our JTs, which I’m not a huge fan of, but I’ve found an issue w mine that’s repeatable specific to the defrost mode:

When I have the defrost/windshield air on and have auto mode off, i usually start off on HI heat. The system blows hot hot air, almost to the point I can’t hold my hand there. The issue is it blasts the same HOT HOT heat at every temperature to the setting of 61 degrees. Only when I get to LO does it switch to cooling. So to be clear from HI to 61 it’s blowing max heat.

if I then bring it from LO, and then to a mid range temp like 68, it’s a neutral temperature which reflects the set temperature.

This is repeatable (5 times this am) after the Jeep has been running longer than 40 minutes.

Any ideas of what this could be? Issue with the blend door?

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[techteacher]

Did this ever get resolved for you?

 

[NachoRuby]

If you have it set at 61, the jeep will try to warm OR cool the air to 61. That means if it's less than 61 in the cabin, the jeep will blow hot air. If it's more than 61, it will blow cold air.

All auto really does is control the fan speed and direction. The temperature settings adjust based on ambient temperature. For example, I leave mine on 72 all year round. Right now that's heat, but in the summer it's AC.

 

[techteacher]

Turns out there was a TSB for the issue - dealership flashed the computer and all is well now. Defrost will move through the temperature settings as expected.

 

[Ben06]

Sorry to bring up such an old thread but does anyone have the TSB number for this issue, I've searched the forum and online and can't seem to find it.

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