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Defrost issues

608 Views 4 Replies 3 Participants Last post by  esox07
2011 w/ dual climate controls. Sometimes when the windshield fogs over, there is a section of the windshield (directly in the middle) that will not clear. The temp seems to change with the controls, eliminating a blend door issue. Is this normal for the GMT900s? I sat in my driveway waiting for it to clear for about 1/2 hr yesterday.
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Do you have a leak in your cab? Maybe a heater core leak or leak from the outside? If the interior of the cab is wet, it will cause the windows to fog up.
Are you running the climate controls stricktly on AUTO or do you switch it to Defrost mode?

You might get a small area between the two top dash vents that doesn't clear right away, but it should eventually and certainly within a half hour.

BTW, if your little AC button light is on, that is completely normal. The truck runs the A/C system to dry out the air in the cab to help it defog the windows. DOn't turn that off.
With the automatic system it is very important to leave it on auto and with the AC on all year around. Plus, as mentioned, it is important to keep the interior dry, even removing and drying the floor mats on a regular bases.
When I push the front defrost button, the auto light goes out. Is that normal?

I'll run with the A/C on from now on, thanks
Yah, once you hit the defrost button the Auto should shut off because you are overriding the AUTO functions and forcing it to manual mode. Once the wind shield clears up gets warmed up some, you can switch it back to AUTO.
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