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Ac & Defroster Not Functioning - Flashing Light

gdnelis

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gdnelis Enthusiast

gdnelis

Posted
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Posted

DITTO

 

On mine; I can't tell if it kicks on when putting it on defrost but it's definitely not happening as all windows fog up and it's worse with higher blower speeds
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Overclock Enthusiast

Overclock

Posted
Posted

Just an update...

 

Mine's been working so far.

It has warmed up somewhat though so it's not as easy to diagnose. There has only been a couple of times where it was cold enough that the AC light didn't turn on.

 

It's supposed to drop in temperature by the end of the week so I should have a better idea then.

I'll make sure to post my findings.

u118224 Enthusiast

u118224

Posted
Posted

Make sure the system is using outside air in defrost mode. Using the recirculation mode with Defrost will fog up the interior. I didn't notice if the orginal poster's HVAC system was manual or auto.

Overclock Enthusiast

Overclock

Posted
Posted
Make sure the system is using outside air in defrost mode. Using the recirculation mode with Defrost will fog up the interior. I didn't notice if the orginal poster's HVAC system was manual or auto.

 

 

That's very interesting....

I believe that the OP has Manual HVAC as is mine.

Mine is always in "fresh air" mode; I never have used recirculation mode but i'm wondering if it's related and maybe could explain why it happens sometimes (so far)

  • 3 weeks later...
mkilla Enthusiast

mkilla

Posted
Posted

Mine is doing the exact same thing, all windows fog up no matter i try to do. its a big safety issue i would say and should be addressed. I have an appointment to take it to dealer next friday to get it checked out, the only worry for me is that the problem is intermittent, it seems to do it most when its raining outside. Ill post back next friday to let you all know what they figured out if anything but i dont think they will find anything. :P

BTBowhunter New Member

BTBowhunter

Posted
Posted

I've experienced the fogging problem 4 times now. It seems to happen when outside temps are in the 30's. Thermometer said 35 this last time. Taking mine in ASAP. The last time it occurred was in serious rush hour traffic while pulling a trailer in a construction zone with no berms. NOT a fun time to say the least! :rolleyes:

 

I did not see aything flashing in the controls and the only way to clear th cab was to roll downthe windows :cheers:

tylerjenkins92@aol.com Senior Enthusiast

[email protected]

Posted
Posted

It's funny, on my 01'. It was 22F this morning and I tried the air and it kicked on and started blowing cold air. Suprised the hell out of me, guess mine doesn't have a temp sensor.

savage99ss Enthusiast

savage99ss

Posted
Posted
It's funny, on my 01'. It was 22F this morning and I tried the air and it kicked on and started blowing cold air. Suprised the hell out of me, guess mine doesn't have a temp sensor.

 

 

My wifes 2001 Denali will flash like hell if under 40 degrees. That is a stupid feature. What good does it do???

BTBowhunter New Member

BTBowhunter

Posted
Posted
Looks like it's 2010's that are having this issue.

Btbowhunter... is yours auto climate control or manual?

 

 

It's a manual control

 

Taking mine in tomorrow. Called in and explained the problem last week and when I called in again today ( after not hearing back) I was told no one there ever heard of such a thing. I'm not happy at all with the dismissive attitude I got from the service rep. I'll be printing this thread and another to let him know that I'm not the only one who's experienced this problem.

Overclock Enthusiast

Overclock

Posted
Posted

It's been pretty cold here and I haven't had the issue.

From what I recall... it usually happens to me when it's warmer.

 

I dont' know if this makes sense or not....

You can't manually activate/deactivate AC after a certain temperature.

If AC is deactivated by the driver on purpose... I'm wondering if it "locks" that in if the temperature drops. This would mean that AC is off and because it has reached the cold threashold; It's locked that way.

 

There was one day between the cold spell that it warmed up to be above the threashold. When I put heat on; the AC light automatically was on in all settings.

 

It's hard to describe what I mean in text.

I hope you guys understand and maybe relate.

  • 3 weeks later...
servicetech New Member

servicetech

Posted
Posted

My 2010 2500HD Service Truck is doing the exact same thing and I would love to know what the fix is before I surrender it to the dealership. My problem is intermittent and sometimes starts off working and starts fogging up an hour later. After it starts fogging up if you press the manual A/C button it blinks 3 times and I know at that time that the compressor is not cycling. Later in the day it may work just fine. I was thinking maybe the pressure switch on the A/C system is faulty. Has anybody fixed theirs?? Paul

ken1mod Senior Enthusiast

ken1mod

Posted
Posted

The compressor pressure switch will not allow the unit to run when temps are in the 40 ish range or below. Looks to me that the system is working perfectly.

 

There will always be atmospheric conditions that the defroster was not designed for. If the weather warms up to 60 or so, the compressor/ac should operate normally. Glass should clear when the heater warms up.

 

ken

pjp Enthusiast

pjp

Posted
Posted

I don't believe that it's a newer issue as my 2008 did the same thing this past weekend. I tried to turn the defroster (with a/c) after running through falling slush and it flashed 3-4 times and went out. It was on "auto" so I just turned the blower up to high and dealt with it. I believe it's designed that way as a safety issue for the a/c pump and trying to keep the oil circulating in very cold temps...

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