Smoke coming up through defrost vents??
 

I have never come across this problem in any of my previous vehicles. I you try to run the heater, it pours massive smoke through the defrost vents. If you DONT use the heater smoke still comes through intermittently. Has anyone ran into this before? Is this a heater core? The heater blower motor has been making bad noises for awhile now. Any help would be greatly appretiated, thanks.

Sounds like a heater core issue.

Thats what I was figuring, I just cant figure out what else it could possibly be. Atleast they are cheap...are they a pain to replace on these trucks? I have never had to do one...yet. Does anyone know how you tell if you have a "high output heater"? My dash says I do but I know that doesnt mean squat considering that could have come from anywhere.

Is it smoke or steam?? If it is smoke, it is not the heater core. I would suspect the blower motor. Smoke means something is burning. there is nothing in the heater core to burn. It can steam and fog up the windows if it is leaking though.

Ive had that happen once...Truck had been sitting for a while...>Think a mouse made a little home somewhere...It hasnt happened since

I believe it is steam...it just poured out so massive and so fast that I panicked and shut everything down as quickly as I could!!

Is there any smell?? coolant, electrical, and you mentioned you blower has been sounding funny, might want to consider replacing it while you are in the area.

I had planned on pulling it all apart. The noise that I am hearing could easily be the blower wheel (something in it maybe). The smoke (as I called it) is actually steam...it fogged my windshield up in seconds. Autozone has different part numbers on their heater cores depending on if I have a high output heater or not and I don't know how I can tell that. I have also noticed that I have to keep adding water to my radiator, so it makes sense to me that the core is leaking. But I haven't noticed antifreeze smell in the cab. But if I have it all torn apart I will just replace the core no matter what, its cheap enough.

high output is a larger size than the standard one
take it apart first so you can match the size
although I did put the HO in mine by altering the box ( had to remove the rib the core located on)

i had kind of the same thing happen to my 98. what mine was is one of the hoses on the heater core started leaking and blowing antifreeze up on the windshield. it sounds like yours is different as you said smoke but i figured i would offer my experience. it is easy to determine if it is antifreeze.

I have a F250 and I just had to turn my defrost off due to smoke and burning smell coming through the vent. When I tried to turn it back on the fan wasn't working. I am thinking its the blower motor but burning smell concerns me. Does anyone have an idea what the problem could be?

That, or the blower motor resistor is opening up. You should open up the plenum and investigate.

For future reference, you'll get better help if you start a new thread when asking a question. I fear that a lot of folks will see this thread and respond to the person who started it over 3 years ago whose problem may not be the same as yours.

I agree . debris on the resistor is possible also . Thread Idea is good also .:-drink

Okay will I will open it up and check. Thank you for the replies. I have just signed up for forum and checked for people with same problem didn't even look at the dates. Thanks again.

96 ranger
 

Just replaced heater core yet still having the same issue!!! Steam comes out of the vents!!! Only when I either turn it off or turn temperature to cool, does it stop
. HELP!!!!!