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Rear Heat Blowing Cold Air

11K views 11 replies 5 participants last post by  electbc 
#1 ·
I don't drive our '09 often, but happen to have it over the weekend. I noticed the air coming from the vents in the rear is cold when the temp control is on full heat. The front temp control is also on full heat, the rear controls are enabled at the front, I checked anti-freeze level and it is full.

I did a search on here to see if anyone else had a similar issue, but had only two hits and they were no help. Thought I would see if anybody else experienced this?
 
#3 ·
Welcome to the forum.
Looks like someone didn't come back to post the repair. That happens often. Year and build (trim level) of your Acadia?
 
#6 · (Edited)
Heater lines would be (should be) full of engine coolant (anti-freeze).
 
#10 · (Edited)
Are the to-rear HVAC lines a separate entity? And are they the same lines for both heating/cooling?
They're in a 4-tube bundle running along the bottom of the vehicle on the passenger side. one inlet/return pair for the A/C, one pair for the heater (at least on the Lambda platform).
 
#12 ·
Just my .02. Cycle the rear heating control through all the temp range, and modes. I had an issue with my 08 where the upper vents blew cold, sometimes even after the warm coolant should have been warming up the rear. I had to cycle through all the settings and then it got warm.
 
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