Grand Caravan Frosts up a LOT! Help!

[nickbuol]

OK, this problem has been going on for a few years, and I keep telling myself that I am going to find out why it is happening, so today is the day.

Every winter (cold here in Iowa) our Caravan will decide that it is going to frost up on the inside of the windows while driving it.

Here is a common example. We will pull the unfrosted/unfogged van out of the garage, drive around for an 30 minutes, an hour, 2 hours, it seems to vary, and then it will decide that it is just going to start fogging up. Usually the side windows fog up first and then frost over in about 30 minutes, then it spreads to the front windshield. Problem is that when it gets to the windshield, it will be clear one minute and LITERALLY within 45 seconds, the whole thing will fog over, and it is a battle to get it clear again before it actually start to frost up on the inside. I've tried blasting heat, turning the defrost on (hot or cold, make no difference), and the only thing that seems to start helping is if we open the windows, which is a pain since it is cold outside.

I've heard that this can happen when it is REALLY cold, like zero degrees F, but I am talking about anytime below 32 degrees F for the frost, and even in teh upper 30's for the fog/

This is a 1999 Grand Caravan Sport (3.8L) with 110k miles, but has been doing this since it had 30k miles on it (maybe longer, we are the second owner).

Please help!

[typesix]

When it starts fogging up, is there a smell associated with it?

[nickbuol]

Originally Posted by typesix

When it starts fogging up, is there a smell associated with it?

None that I have noticed in the past. Why? What are you thinking? I am open to trying just about anything.

Someone who doesn't know much about cars (not saying that I do either) thought that it was a moisture problem and that there is a lot of moisture in the air/heat system... Not sure, but just thought I would throw that out. If there was, why hasn't it "dried up" over the years? Is there a drainage clog? Maybe not even on the right track here.

[GTP Dad]

There is a possibility that you have a leak in the heater core. Even though you don't get any smell there is a chance that the core is leaking. That would account for the windows fogging up and you having a hard time clearing the windows.

There is also a possibility that there is a blocked drain and when the car warms up sufficiently that the moisture is picked up and blown onto the windows. The drain should be located somewhere on the firewall. Run a heavy wire through it and if there is water in the ducts it should drain out. I would check this first.

[eldiablo1100]

sounds like it could be you're not getting air circulation in the car. are the air controls stuck on recirculate

[nickbuol]

Originally Posted by eldiablo1100

sounds like it could be you're not getting air circulation in the car. are the air controls stuck on recirculate

The button itself (since it lights up) claims that I can turn it on/off... I guess that still doesn't mean that it is working.

[KManiac]

This could be only two things, a leaky heater core or a ventilation system stuck in "recirculate". If your car has A/C, the compressor should operate when the "Defroster" setting is selected. This allows the A/C system to "dehumidify" the air and quickly clear any frost on the windows. Is your A/C adequately charged with refrigerant? The sudden changes in frost seem to indicate that maybe your A/C compressor is cycling during defroster operation, possible due to low refrigerant level. If the compressor is cycling along with the fresh air door stuck in "recirculate", you will see the windshield go from clear (compressor on) to fogged (compressor off) in less than a minute. Focus on these areas and I think you will find your problem.

[Stretch58]

Originally Posted by KManiac

This could be only two things, a leaky heater core or a ventilation system stuck in "recirculate". If your car has A/C, the compressor should operate when the "Defroster" setting is selected. This allows the A/C system to "dehumidify" the air and quickly clear any frost on the windows. Is your A/C adequately charged with refrigerant? The sudden changes in frost seem to indicate that maybe your A/C compressor is cycling during defroster operation, possible due to low refrigerant level. If the compressor is cycling along with the fresh air door stuck in "recirculate", you will see the windshield go from clear (compressor on) to fogged (compressor off) in less than a minute. Focus on these areas and I think you will find your problem.

As far as the A/C is concerned, it won't operate when it gets cold (I think it cuts out in the upper 30s). One check to see if the system is stuck in recirc, is put it in outside air mode with a window open. Turn the fan on high, then shut the window. When the window closes, if you can feel the pressure change in your ears as the car pressurizes, it is in outside air. The car will not pressurize if it is in recirc.

[RIP]

There is a built in test function for your air circulation system. It checks the circuits and door movements for all the circulation modes. Unfortunately, I don't remember the sequence of buttons you have to push to engage the test. CAN ANYONE HELP WITH THIS?

[vipergg]

you need to run the calibration tests on the blend doors and it will probably fix this.
1. Set blower to high.
2. Set mode position so that it blows out the front vents only.
3. Set temp to cold.
4. Depress the Wash and Wipe simultaneuosly for 5 seconds until all lights turn on.
5. All leds will turn on for 5 seconds.
6. Test is running when wipe and wash are alternately flashing .
7. end of test the wiper button should be flashing , push wiper button to exit test

[greg63]

My 2000 Grand Caravan Sport (3.3L) just started fogging up in temperature between 30 and 35. I took it to the dealer and they could not find anything wrong with it. Did you ever get your problem solved.

[nickbuol]

Originally Posted by greg63

My 2000 Grand Caravan Sport (3.3L) just started fogging up in temperature between 30 and 35. I took it to the dealer and they could not find anything wrong with it. Did you ever get your problem solved.

Yup... I bought a new van. :-)

Never did get the problem resolved with the old one. Sorry. My best guess was that there was something stuck that was keeping too much moisture in the air, and thus, when the heat was blowing, it was creating condensation on the windows that would frost up.