Burning electrical

[squeekyM]

Tonight on my way home my cab filled with smoke VERY quickly as soon as I turned the heater on. Anyone ever had this happen to them?

I started the truck, let it warm up for about 2 minutes then took off. As soon as I started it I set the HEAT to HOT, but left the vents selector at OFF. After driving for about 10 minutes, I pushed the selector to heat and immidiately smell something burning....the cab started filling with smoke. I thought the truck was a goner....I quickly pulled to the shoulder, shut off the truck, jumped out and very quickly walked away. Needless to say, the truck didnt fry.... after about 10 minutes of letting it sit, I jumped back and turned off the heater, and drove off without any issues.

A few months ago during summer, I noticed a similar smell when turning on the A/C; I thought it was just from letting the truck sit for weeks without running it, maybe something was growing in the vents??? We today that smell became very strong and was followed by smoke. I am curious if anyone else has dealt with this before? How should I trouble shoot this without burning my truck to the ground?? Thanks in advance.

BTW my truck is a 1986 F250 4x4 w/t-19

 

[The Warden]

I would remove the heater blower motor and clean all the leaves and gunk out of the a/c condenser and the heater core. My guess is, a leaf was smoldering on the heater core and that's what you smelled.

Leaves and such in there are very common, reduce the airflow, can stay damp and cause rust, and are a potential fire hazard. I would do this PDQ just to be on the safe side...

 

[sle2115]

What Warden said, and are you sure it wasn't antifreeze steam? If you are not familiar with it, antifreeze will have a very distinct sweet smell. Mine did exactly this when my heater core went, both times! Smoke the whole cab up to a point I had to pull over and air out the truck.

 

[Agnem]

I can't recall exactly, but in a lot of Ford's with multispeed fans, they put a resistor that is air cooled in the air box. If you have debris up against that, it's going to set fire to them for sure. I'd be pulling your blower and checking for junk. Clean your cab drains while your at it.

 

[adrianspeeder]

I vote for leaves or a nest against the blower resistors.

Adrianspeeder

 

[84TD]

I had that exact same senario a few days after I bought my truck. I thought my truck was about to burn to the ground... Let it sit for 10 min and all clear. That was 3 months ago, no problems. I agree with the rest of these guys, prob a leaf or something.

 

[MIDNIGHT RIDER]

I also vote for leaves and trash, trapped in the air-box.

I recently removed my blower-motor and fished out half a five-gallon bucket full of leaves, sticks, dead mice and birds, and lots of black ****.

Another possibility, if the truck has a turbo that resides close to the air-box, is that the exhaust is melting the plastic air-box and smoking up the cab; don't ask me how I know this.

 

[squeekyM]

Thanks for the responses. Is this airbox accessable from inside the cab....similar to replacing the heater core, removing the glove box etc....or is this the thing up against the firewall in the motor compartment?? Thanks again.

 

[The Warden]

You'll want to pull the fan blower motor. It's accessible from the engine compartment, and is only 5 or 6 bolts. Actually pretty easy to remove.

While you're at it, you may want to pull the cover off the a/c evaporator box (I said condenser earlier; I misspoke...meant to say evaporator ) and see if anything in there needs to be cleaned as well. This cover is also accessed from the engine compartment, and is the cover on the inboard side of the box that the a/c lines go into, right by the passenger's side cylinder head.