I have a 2011 GMC Sierra

WABASHMIKE

MEMBER
2011 GMC SIERRA
8,500 MILES

I have a 2011 GMC Sierra. My question concerns the defrost. On other vehicles I have owned when using defrost the AC engaged to assist with the removal of vapor on inside glass surfaces. On the 2011 Sierra below a temperature of around 30 degrees the AC will not engage. Is this normal?

Mike

4 Replies

WABASHMIKE

MEMBER
3 POSTS

If not normal how do I repair it, or am I doing something wrong?

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Wednesday, January 30th, 2013 AT 2:02 PM

HMAC300

MECHANIC
48,601 POSTS

No it's normal even on the earlier trucks when it got below freezing the a/c didn't work. That is ok it is actually set up to do that so don't try to "fix" it to make it work. It is made to do that, don't worry about it. It does no harm to a/c or heat

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Wednesday, January 30th, 2013 AT 3:23 PM

WABASHMIKE

MEMBER
3 POSTS

Sir,

If the disengagement of the AC is the standard set up, how do I keep the interior from steaming up below 32 degrees?
This morning for instance, the temperature was 25 degrees I had the heater set on defrost and the fan on high and still needed to roll the window down partially to try to keep the interior from steaming, and then it was still a battle. Yesterday the temp was above 32 and even with a rainy day with the AC engaged the interior steam was removed easily and stayed off. Is there some setting that I am missing?

Mike

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Thursday, January 31st, 2013 AT 2:21 PM

HMAC300

MECHANIC
48,601 POSTS

Have your heater core checked for a leak first and excessive water on floor will do that also make sure thetemp on truck is about 210 some degrees when warm. If air temp outside is below 32 and truck is cold that will also happen due to normal condensation of cold to hot. But normally it's water on floor like alot of snow came into truck rfrom getting inside. If yo have never lived in a cold climate that is one of the things the fogging normally will go away with inthe first mile or two of driving in colder weather.

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Thursday, January 31st, 2013 AT 3:00 PM