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Discussion Starter #1
After not using my car for 2 months due to COVID, it now is having issues cooling.

The weird thing is the front vents blow a little bit cool...the rear seat vents are piping hot.

What would cause the extreme difference between the two? I'm super confused.
 

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2016 Malibu 1LT 1.5T
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I am a little bit confused as well. You mention the front vents are a little bit cool but there is an extreme difference between the front and back? Is the front cooler and dryer than warm humid outside air after a couple minutes? Also is this manual controls or the automatic dual zone?

If the car wasn't used at all, my first suspicion would be blockage then a damaged/chewed wire leading to a faulty blend actuator. But first, this problem is ONLY the front (cold) vs rear (hot)? If you swap forward vs windshield (defog/defrost) vs floor all front vents are cold as normal?
 

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Discussion Starter #3 (Edited)
Yes it's odd. Let me clarify now that i've had time to look at it a bit more.

I have manual controls.

The front panel vents blows 'cooler' air. Floor and rear are HOT (like hot to touch). When I say 'cooler' I mean slightly cooler than outside air (maybe a couple degrees). It's not COLD by any means.

Things I've checked:
  • AC pressure/level is in range
  • Compressor turns on and continues to run when AC activated
  • Fans kick on
  • Blower fan works
  • AC stainless lines are COLD and condensating
  • Ambient temp is accurate
  • Adjusting temperature dial to hot warms impacts temperature correctly (warmer air)
  • Disconnected battery for 30 mins to see if something had to reset
 

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Discussion Starter #4
The actuator might account for the differences in temp but, could that be blocking all cold air?
 

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Ever replace the cabin filter? Also, where you able to check the high pressure side or just the low side?
 

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Discussion Starter #6
I haven't replaced the cabin filter in awhile..I'll pull that today. I was only able to check the low side pressure.
 

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Pulling the filter out should help air flow and increase cooling.

Be careful if you choose to add freon, as the low pressure only reading is not adequate to correctly install the proper amount and you will likely overfill the system (which can also produce the lack of cooling).
 

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Discussion Starter #8
OK pulled out filter and no change. Another interesting note..it finally cooled down here today (70 degrees). I went for a drive and just put on the vent (coolest setting, AC off) and the vent was hot. Way hotter than the outside temperature.

Makes me think this is something related to a temp sensor or actuator since its happening outside AC system as well?
 

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OK pulled out filter and no change. Another interesting note..it finally cooled down here today (70 degrees). I went for a drive and just put on the vent (coolest setting, AC off) and the vent was hot. Way hotter than the outside temperature.

Makes me think this is something related to a temp sensor or actuator since its happening outside AC system as well?
Sounds like an actuator (blend door -- mixes the hot and cold air flow) problem. You should get cool air on all the vents after a few miles (assuming that the fan is on max and that cold is selected). Safe to assume that the warm rear air has reasonable (normal) flow?

Go for another drive, with fan at max, max cool (with or w/o AC). Cycle the temp selector between max cool and max hot and see if there is a difference (both front and back). Give it a minute or two to settle in each new position.

Also, check the temp right after start-up (cool engine, max fan, max cool, on a cool day w/o AC) as there is no way it should be hot then.
 

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Sounds like an actuator (blend door -- mixes the hot and cold air flow) problem. You should get cool air on all the vents after a few miles (assuming that the fan is on max and that cold is selected). Safe to assume that the warm rear air has reasonable (normal) flow?

Go for another drive, with fan at max, max cool (with or w/o AC). Cycle the temp selector between max cool and max hot and see if there is a difference (both front and back). Give it a minute or two to settle in each new position.

Also, check the temp right after start-up (cool engine, max fan, max cool, on a cool day w/o AC) as there is no way it should be hot then.
Need help with similar issue 2016 LT it was blowing hot on floor and rear vents last month, i took it to the dealer, they changed “Mode door actuator“ it seemed to work when i left, but now its doing the opposite! Its blowing cool air on floor and back vents when select heat!
 

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Auto or manual controls? The actuator may need to be (re)calibrated, which the dealer may have forgotten to do.
 
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