CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

2006 GMC Sierra 1500 - recycles all the time

cab fresh air inlet or recycle door gos to recycle all the time even in the winter time and fogs up inside the cab. when you hit defog, door gos to fresh air mode, 2 min later its back in recycle mode

Sounds like a bad HVAC control module.

https://www.partsgeek.com/gbproducts/AC/18328-05338424.html?utm_source=google&utm_medium=ff&utm_content=NC&utm_campaign=PartsGeek+Google+Base&utm_term=2005-2006+GMC+Sierra+1500+HVAC+Control+Module+Dorman+Front+05-06+GMC+HVAC+Control+Module&utm_source=google&utm_medium=ff&utm_campaign=PartsGeek+Google+Basecid=6774379819&aid=79287199093&keyword=833350606290%3A%3Apla-833350606290&kid=833350606290&gclid=EAIaIQobChMI3POAlJTz5wIVFKvsCh2E7A3hEAQYBSABEgLKt_D_BwE

Tester

@Tester could be right, but you might want to try recalibration first. With car off, remove HVAC fuse for 10 seconds. Start car and don’t touch anything for 40 seconds. The system self calibrated. I got this info from another forum.

the controller that is in there now is the 3rd one. frist i put in dorman 599-211 did not work then, then i replaced it with another 599-211 still not good. tech support said to try dorman 599-013 still not good.

another thing i noticed is i have to turn call for heat way down like around 61 degrees but still heats you out of the cab if you turn it down to 60 degrees heat shuts of all the way