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I've noticed in the last week or so that the A/C on my 2011 Terrain SLE2 has started changing speed settings all on it's own. (It's NOT in Auto Mode)
I'll be driving along and the air will either change down or up by several speeds. (almost like when I'ts connecting a phone call and everything turns down)
Again it's NOT in Auto Mode.

Has anybody else experienced this?
 

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Very odd indeed. Since the car does have the ability to adjust the fan speed (when receiving/making a call with bluetooth or OnStar) my guess is something is malfunctioning within your ECM. I would ask the dealer to reprogram it - might just be a bug or bad software loaded onto yours
 

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There is a bulletin for a/c concerns, Have your dealer check into this:

#PIT5115: Erratic HVAC Operation C67 Or C68 - (Aug 30, 2011)


Subject: Erratic HVAC Operation C67 or C68


Models: 2011 Chevrolet Equinox

2011 GMC Terrain

With No Codes or B101E 4B




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Customers may comment on an intermittent HVAC operation when changing modes or unwanted temperature changes or A/C operation such as A/C turns off unwontedly and can be turned back on. During diagnostics the technician may not be able to duplicate the concern due to the intermittent condition. Using GDS check the HVAC control module for any diagnostic trouble codes (DTCs). It has been found that this condition may not set any DTCs, however you may find a DTC B101E 4B for a calibration not set or may have set after performing a HVAC Actuators Learn. This concern may be caused by a poor connection within the actuator wire harness.

Recommendation/Instructions:
When performing diagnostics if the fault is current for one mode not working, Example: The temperature mode is inoperative or may not fully sweep, Perform the normal Service Information diagnostics this may lead just to a faulty actuator. If the condition is intermittent and after checking the connections at the HVAC module and the actuators the cause of the fault is not found. Replace the wire harness from the HVAC module to the actuators/evaporator sensor and apply dielectric grease as per Service Bulletin # 09-06-03-004D for repairing fretting corrosion.
 

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I don't think I have problem this pertains to since it does not change temp or fan on it's own.

But curious how others deal with this:::per dealer what mine does is normal, but is going to take some getting used to...Regardless of auto or non-auto, when you adjust temp, say to make colder. You get some cold air then it get's warmer again. Then you have to adjust little more colder to actually get colder air. Same thing in reverse. You want warmer. You adjust few degrees. Get warm air, then colder. Then you adjust few more degrees then it says warmer.

Had dealer reprogram and check out. They agreed with me that it was better when temp knob just went to heater core valve...

Thoughts?
 

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pawjr74 said:
I've noticed in the last week or so that the A/C on my 2011 Terrain SLE2 has started changing speed settings all on it's own. (It's NOT in Auto Mode)
I'll be driving along and the air will either change down or up by several speeds. (almost like when I'ts connecting a phone call and everything turns down)
Again it's NOT in Auto Mode.

Has anybody else experienced this?
My wife's 2010 Terrain SLE2 does the same thing. The fan seems to increase to Max for a second or two and then drop back down to the setting she had it on.

I see the TSB for the 2011, is there one for the 2010?
 

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Crap like this makes me wish for the old fashioned a/c. You manually moved the lever to the desired temp. If you wanted it cooler you moved the lever a little more to the left. None of this computer settings, downloads, uploads, virus's etc. :beer:

Mine operates like scottb's. I've been in cars where you never felt and difference in the temp during the automatic adjustments - no cooler or warmer spurts.
 

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I haven't noticed this issue on mine but there is a sun load sensor on the dash that increases fan speed when driving into the sun to compensate for the suns additional heat coming through the windshield. Could be what's happening.
 

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Never noticed that. I'll have to watch for it.
 
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