It's awfull foggy in here !!!!

skidooridr · March 29, 2005

Hope someone can help.

i have a '99 silverado 5.3L 4x4 x-cab

This thing fogs up so badly sometimes there is actually water running down the winshield! I took it to a dealer,and they did a "pressure test" on the "cooling/heating" system,and said there were no leaks. I don't smell any antifreeze either. It doesn't seem to matter if i'm recirculating,or bringing in outside air either. Some days as soon as i drive it for 1-2 minutes-all the windows are fogged [including the rear window]. i can blast the defrosters at high speed,but it just can't clear the windows enough,so i usually have to wipe them.

the only thing that did help was putting anti-fog spray [from my snowmobile helmet shield] on the winshield. that helps for a couple weeks on the winsheild,but not as long on the side windows.

any ideas ??? Thanks in advance.

71GMC_3/4T · March 29, 2005

You got Air Conditioning?

If not, you're probably not ever going to get it to clear up.

If you do, it should be drying the air when it's on defrost. Check the compressor and be sure the A/C is working...

Mark_in_Tulsa · March 29, 2005

Make sure there is no moisture at all in the truck. You may have to pull up some of your carpet to do a real good check.

But if you can't find what is causeing it, then try this out.

http://www.motosolutions.com/

This is what the lemo drivers use in there cars. I personaly have never used it, but it gets great reviews.

Also where you located at, and whats the weather been like, elevations....etc

skidooridr · March 30, 2005

You got Air Conditioning?

If not, you're probably not ever going to get it to clear up.

If you do, it should be drying the air when it's on defrost. Check the compressor and be sure the A/C is working...

<{POST_SNAPBACK}>

YES, Have air. i tried running the air... with the defrosters the other day-.

just didn't seem to make much difference. ?

Also- when it's parked outside,and really cold out- it's not as bad as when

i pull it in the garage for the night,and start it up in the am- really bad then .

skidooridr · March 30, 2005

Make sure there is no moisture at all in the truck. You may have to pull up some of your carpet to do a real good check.

But if you can't find what is causeing it, then try this out.

http://www.motosolutions.com/

This is what the lemo drivers use in there cars. I personaly have never used it, but it gets great reviews.

Also where you located at, and whats the weather been like, elevations....etc

<{POST_SNAPBACK}>

Funny you should mention the weather. When it's really cold out,and the truck is sitting outside and i go to start it up- it's not as bad , as when i pull it in the garage

[ warmer ]for the night-then go to start it in the morning-really bad then. Someone told me there's an "interior filter" in the ventilation system- you know where that would be,Mark?

Mark_in_Tulsa · March 30, 2005

Make sure there is no moisture at all in the truck. You may have to pull up some of your carpet to do a real good check.

But if you can't find what is causeing it, then try this out.

http://www.motosolutions.com/

This is what the lemo drivers use in there cars. I personaly have never used it, but it gets great reviews.

Also where you located at, and whats the weather been like, elevations....etc

<{POST_SNAPBACK}>

Funny you should mention the weather. When it's really cold out,and the truck is sitting outside and i go to start it up- it's not as bad , as when i pull it in the garage

[ warmer ]for the night-then go to start it in the morning-really bad then. Someone told me there's an "interior filter" in the ventilation system- you know where that would be,Mark?

<{POST_SNAPBACK}>

Yeah the 02's and older do have an air filter for the inside, which I do need to replace, and I don't exactly know where its at. But I don't think that would be the prob. I know you can get the replacment air filter at most auto stores or the stealership for not very much.

Wingnut · March 30, 2005

Well, you guys happen to be in the right place....

***In-cabin air filter replacement procedure***

skidooridr · March 30, 2005

Well, you guys happen to be in the right place....

***In-cabin air filter replacement procedure***

<{POST_SNAPBACK}>

YOU THE MAN , WINGNUT !!

GM-Tech · March 30, 2005

This thing fogs up so badly sometimes there is actually water running down the winshield!

If it's that bad, there has to be coolant or water getting into the interior or hvac case.

skidooridr · November 15, 2005

Mark, or anyone who has a 99-up . Carrying this on from last spring if you don't mind..... now that it's getting colder out i turned on the defrosters, and noticed that the " recirculate/ in-let air " button is automatic. When i have the defrosters on, it automatically goes to the " inlet air" mode. I think that should be the opposite.. with the defrosters on shouldn't it be in the "recirculate" mode ???? Can someone check their system & see if that's just the way GM has it programmed ? I tried to physically move it to "recirculate" [ with the button].. with defrosters turned on... but it kicks back to "inlet air" mode Seems to be backwards .... no ?

Make sure there is no moisture at all in the truck. You may have to pull up some of your carpet to do a real good check.

But if you can't find what is causeing it, then try this out.

http://www.motosolutions.com/

This is what the lemo drivers use in there cars. I personaly have never used it, but it gets great reviews.

Also where you located at, and whats the weather been like, elevations....etc

<{POST_SNAPBACK}>

Funny you should mention the weather. When it's really cold out,and the truck is sitting outside and i go to start it up- it's not as bad , as when i pull it in the garage

[ warmer ]for the night-then go to start it in the morning-really bad then. Someone told me there's an "interior filter" in the ventilation system- you know where that would be,Mark?

<{POST_SNAPBACK}>

GM-Tech · November 15, 2005

This is from the description and operation of the system...

"In order to reduce windshield fogging, outside air is circulated when the mode switch is in the defrost or defog positions."

So the answer is, it is designed that way.

DenisMcG · November 15, 2005

My guess is that you are having a problem with the recirc system. As GM-Tech stated, fresh air has to be pulled in, then heated in order for defrost to work properly. It sounds like you are stuck in recirc mode. This simply heats the cabin air which then condenses on the cold glass. It gets worse while you drive because any moisture in the cabin, including the moist air coming from your lungs, quickly saturates the air. I suggest that you check the recirc flapper to make sure it isn't stuck. It is not likely the filter, if it was plugged you would get very little air out of the vents.

Good Luck,

Denis

skidooridr · November 15, 2005

My guess is that you are having a problem with the recirc system. As GM-Tech stated, fresh air has to be pulled in, then heated in order for defrost to work properly. It sounds like you are stuck in recirc mode. This simply heats the cabin air which then condenses on the cold glass. It gets worse while you drive because any moisture in the cabin, including the moist air coming from your lungs, quickly saturates the air. I suggest that you check the recirc flapper to make sure it isn't stuck. It is not likely the filter, if it was plugged you would get very little air out of the vents.

Good Luck,

Denis

<{POST_SNAPBACK}>

Denis,

where would this "flapper" be? Is it accessable without taking the dash apart ? is it at the top or botom of the dash ? Thanks for both of your posts. it's all finally making sense to me,as far as the function of the recir. system.

DenisMcG · November 15, 2005

I am not 100% certain as I do not have a 99. But it should be just behind the glovebox. With the engine running and the heater control know in defrost (AC off) push the recirc button and listen for the actuator and flapper moving. Try it a few times as it might be quiet. Of course, if the actuator or controller is the problem, then you won't hear anything.

Denis

polarisridr · December 6, 2005

I am not 100% certain as I do not have a 99. But it should be just behind the glovebox. With the engine running and the heater control know in defrost (AC off) push the recirc button and listen for the actuator and flapper moving. Try it a few times as it might be quiet. Of course, if the actuator or controller is the problem, then you won't hear anything.

Denis

<{POST_SNAPBACK}>

To GM EXPERT & Denis & all who helped me on this subject :

That's exactly what the problem was. I took the truck back to the dealer [again]

said some "reliable experts" mentioned the acuator could be bad.... yes i tried to

listen for the "butterfly" to open & close as i moved from "fresh air" to "recirc".... but i could tell nothing was happening. I had an extended warranty on it that i found would cover it. They tore into it & found the actuator burned up. put another one in & it didn't work either ! Then the GM tech searched & found a wire from a harness had bin "pinched" from the factory upon installation & that's what caused the actuator to burn up. Fortunetely he caught it before the new one burned up too. Total labor time was covered [ 10 hours] . 2 years ago i took it in not knowing

what the problem was , so couldn't steer them in ANY direction. They found nothing wrong. So glad i found this site just by accident & thanks to you guys i was able to tell THEM what the heck the problem was.

PS... I was logged under skidooridr , but for some reason couldn't log in on that name this AM. THANKS AGAIN