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Cabin vents blowing steam

569 Views 7 Replies 5 Participants Last post by  silverado002
Hey guys,

So on my drive to work yesterday about a 2 or 3 miles on the road from pulling out of my driveway, i noticed my side windows fogging up, so I turned my defrost up from Med-Low to Hi. it was dark out so I really couldnt see much and then the next thing i know about 30 seconds later i cant see out of my windsheild. I was looking for a good spot to pull over to find something inside my truck to wipe my windows off so i would not be late to work and eneded up putting the heat on my feet and driving with my front windows down the rest of the way to work (it was a long, cold 20 minutes.) The temperature outside was about 15 degrees coming from west michigan. I did everything I normally do to prepare my truck for driving in the cold after sitting outside all night in the snow. I Started it 10 minutes prior to leaving and the steam problem started happening once my engine hit about 110-120. I Initially thought I had blown my heater core but after making it into my parking low at work i didn't see or smell any antifreeze anywhere. I warmed it back up at lunch time and drove around going througha few cooling cycles heating the coolant up to around 210 degrees and there was no steam. just wondering what went wrong or if my truck just fixed itself. (I wish it always did that))
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When you post with questions, we need to know what year truck you have, and what engine. Is it 2WD or 4WD? I see on your profile page that it is a 94 and I see its 4 WD. A 1500 I assume. So I know that my 97 has a different AC and heat control system than yours does, but whe I put mine in defrost, my AC compressor kicks off and on, no matter how hot I set the temp, and how cold it is outside. You could try pulling the wire connector off of the AC compressor, and see if that helps, although if there is steam, that is a leaking heater core, most of the time. Hes there been any stop leak added to the system ? What shape is the coolant in ? is it nice and green, or red, or is it rusted ? If everything is nice and clean in there, you can try some alum a seal stop leak. If not then you need to do a flush and fill with new antifreez and fresh water, then do the alum a seal. View attachment 114545
My bad, The truck is a 1994 GMC 1500 with a 350 and 4wd. It was about 15 degrees or so outside. coolant is at the right level. I have put about 150 miles on my truck since that happened Monday morning and I havent seen a decrease in coolant levels and the steam problem has not occured any other time since the first.
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Check the coolant level in your reservoir. Could he also have condensation/water in the heater box that is vaporizing because it didn't drain properly?
I have been asking around as what it could be and I have heard also that it might just be condensation on the in the box too. And I was just wondering causes of to why that would happen.
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