reyderz

Anyone know what causes this? Someone told me it's the heater core leaking into the airconditioning system.

Scubanme

I don't know exactly how the ehater system works on the C-5s, but older fogged up when there is a leak in the heater core. Does it smell like antifreez in your car?

IMQUIK

Crack the window a bit when you are "Doing it" :jester

rwj383

This just happened to me about 2 months ago. Yup, it was the heater core. I hope you are still under warranty, too. Get this: the ENTIRE dash has to come out + the intake has to come off the engine + the cowl has to come off...many labor hours. Also, lets hope the mechanic at the dealer has done at least one before or he'll never get it back together right/tight. I dont mean to scare you, but, this was my reality when my core sprung its leak. Has yours totally sprung coolant all over your pass footwell yet?? When mine finally did, it soaked the PCM module and relay/fuse center behind the pass footwell. PLUS, it'll take years to get every bit of coolant out of the carpet. I still feel the slimey feeling to this day. I need to hit my carpets one more time with the carpet cleaner.
Good luck. I hope its not your core!
Robert Judd

Smoke-N-Shot

Heater core... :yesnod:

Special K

I agree it's probably the heater core. But I'm going to try and think a little more positive. It could also be moisture (condensation) in the ducts. If it's the heater core, you should be able to smell it. Do you notice a white discharge from the ducts especially when you first start the air? That would indicate moisture.

Bob
:flag

TheBigGuy

I too had the same problem. Fortunately for me it was a bad " O " ring connection at the heater core. So they only had to pull the intake manifold to get to the problem. Hopefully your problem may be the same. Good Luck !

white93

My windshield fogs up on my '99, but only when the AC has been running for a while. It is not supposed to be routing cold air through the defroster onto the windshield as I have it set, but it seems that is what is happening. I assumed the glass was getting very cool and condensing the high humidity here in NC. The fogged area is immediately over the windshield ducts and doesn't spread too far. I couldn't see an obvious way to check the duct routing but maybe I should??? I don't smell coolant and coolant volume isn't decreasing, so I assumed it was an annoying air leak in the ductwork in the dash. Now I guess I'll worry a bit more and try to get to the ducts.

Cliff99C5hardtop

My windshield fogs up too, but it's on the outside. My problem is when I installed my LS6 intake, I never made sure the vaccuum line on the back of the intake was on securely. My AC comes out all my vents at the same time!! I just have to get my lazy butt to do it.....Just hope it is not the heater, they are very difficult to do.

geck

[QUOTE]I don't know exactly how the ehater system works on the C-5s, but older fogged up when there is a leak in the heater core. Does it smell like antifreez in your car?

:iagree:

LoneStarFRC

:iagree: If you have coolant inside anywhere then I would agree on the heater core theory. If however, it's just water, then that by itself could just be the condensation drain tube clogged or partially clogged.
Mine will fog on high humidity situations with a cool outside air temperature if I keep it in recirc mode. When I switch to outside air mode, especially with the defrost selection, it clears up right away.

Robert

John's vette

Does your AC blow out of all vents? Mine fogs up and it is driven by a vacuum line being eaten by a leaky battery. The acid destroyed my vacuum line that controls which vent the AC comes from. I would look at that if you show no signs of coolant leaks.

reyderz

I don't smell anything. It takes a couple days to fog up and then I have to take a rag and wipe it off to get it so I can see good without other people headlights reflecting on it at night. I'll try to take a pic.

zvette74

How Much?

Vetteman Jack

This is a 14 year old thread. It would be best if you started your own thread, explain what is going on with your car, and then ask for assistance. Besides, the OP hasn’t posted in many years so chances are he’s not going to see this.