heater fan

[FlatBlack77]

plus if you unplug it over summer and get caught in a rainstorm and you need to defog, you are in trouble lol

[philo_beddoe]

Since this is a heater fan thread, although mentioned elsewhere, my truck is like a steam bath or like a hot steamy shower when i turn on the defrost on a cold day after warm up, kind of started all of a sudden. Windows fog up heavy on the inside. Totally clueless. Is moistere getting in somewhere, there is no smell whatsoever.

[AZ87V10]

What's the weather look like there? How cold is it? Humidity level? You're letting your engine warm up first before you turn your HVAC system on? If that's the case, it sounds like you're blasting air that is warmer and more humid onto the windshield than the surrounding ambient air. It's naturally going to condense when that happens. As long as there's no evidence of coolant in that fog on your windows then you're probably fine. Maybe wait for a warmer and dryer day and see if it does the same thing?

[Irish_Alley]

have you checked the coolant level? i know you said it doesnt smell like it but there might be a chance

[AZ87V10]

Well, it's a pretty unmistakable smell when a heater core starts to fail. When the one went out in my Dodge last year, it stunk up the whole cab! Plus, the windows would fog over and you could see the oily residue of the coolant in it. I also had the signature steam coming from the HVAC vents! It looked like smoke but was evaporated coolant. I had it replaced and I still get the occasional smell of coolant whenever I run the heater.
Check the obvious things first like Tim suggested and go from there. It sounds like you might just have moisture build up in your ductwork. You said it's been cold there, the air in the ducts is warmer than the surrounding air and it's condensing like I already said. That seems the most logical culprit if your heater core is fine.

[philo_beddoe]

I'll keep a close eye on those things you mentioned.  It is unseasonably cold up here in MA.

[philo_beddoe]

Warm and heavy rain all day. Nonetheless, it wasnt too bad. I think for the short time i had it unpluged, moisture built up in there.