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Smoke from heater core?

MistahYebba

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Howdy,

I have a lot of coolant consumption. I have to fill up my overflow tank every month with fresh 50/50 because it just disappears.

Surprisingly enough, I NEVER overheat. I drove 4 hours a couple weeks ago to this restaurant I wanted to take the old lady to and the truck ran great. Little scary though... some highways suck down here in Florida...

Anyway, the temp control from cold to hot, if I set it near the middle on warm, smoke will come out of my vents.

If I put it all the way over to hot, it won't smoke, but you can smell a lot of coolant (syrup) and some burny smell. Not desired. So I use my air a lot so I don't suffocate myself from filling up the cabin with chemicals lmao.

So I was thinking what could even do this.......

I imagine that the temperature control slider must have some sort of revolving piece inside, and at one point of that revolving piece, there is some sort of leak at that point causing the smoke to get in.

But the smoke getting through the vents is just a product of the issue, not the final stop.

What's actually causing it to smoke is the big deal. This must be where all my coolant is going?

Anyone got any ideas so I can look into this sooner rather than later?

Thanks so much!!

I know I post here a lot; I really love this community. I wish we could all get together one day in a big mechanic's lot and look at each other's Fords. It would be so cool!
 


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natenkiki2004

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Smoke from the vents is typically the blower motor resistor collecting crud and actually burning it.

However, from what you describe, it sounds like your heater core is leaking. But, a leaking heater core shouldn't smoke. I don't think it could leak anywhere near enough to get on the blower motor resistor, you'd have coolant all over the interior as well.

If I was in your situation, I'd do 2 things;
- Pull the blower motor resistor and check for crud. If there's crud/debris then I'd pull the blower motor and get a vacuum to get it all out.
- Bypass the heater core with a double-male 5/8" fitting. Take the 2 hoses that go into the firewall above the blower motor off and connect them together. If your coolant consumption and smell disappears, it's 100% your heater core failing. Another test that might arguably be easier is to pull the pan/cover below the glove box to take a look at the underside of the heater core. There's a thread on this forum that goes over it's replacement due to leaking, you'll see what I mean in the pictures.
 




MistahYebba

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You know....

from what I recall now.....

There was a bizarre that had just randomly disappeared about a month back. A terrible smell from the AC, but only if the fan speed knob was set to "2". It would smell really bad, similar to burning plastic or something, but worse.

When that randomly went away I completely forgot about it. But honestly, I wonder if it's connected and somehow went from emitting a bad smell on a certain fan speed, to now releasing smoke at a certain temp position.

I wonder if they are somehow related. It's funny because like 4 months ago I was going to take about my air/heater/blower/core area and vacuum it for leaves and debris... but it was getting dark that night and I just didn't get to it. Never did get back to doing that.

Now it's like it's catching up with me. :)

Now just to figure out how smoke and coolant loss could be related. I will look into examining that blower resistor.
 




natenkiki2004

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The blower motor resistor gets hot on any position other than full blast on the fan control. That may help you diagnose.
 








MistahYebba

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The blower motor resistor gets hot on any position other than full blast on the fan control. That may help you diagnose.

So Nate I wonder why it only happened on position 2. So bizarre.

And why smoke only comes out when it's moved to a very particular temperature. Also very bizarre.

WHAT A WEIRD FREAKIN TRUCK MAN.

But I brag about you and how long you've been helping me with my baby. Haha :)
 




MistahYebba

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Photo of leaves and debris catching fire and smoking in the blower motor resistor from my '94. http://www.explorerforum.com/photopost/data//3914/medium/IMG_0532.jpg

I hear leaves sometimes. That's why I mentioned my intent to clean it out at one point, but I never got to it.

I find it hard to believe it could create a constant supply of smoke for so long? It's been smoking when I turn it on half heat for like a month now, I just haven't cared.

it HAS to be on half heat though. Cold air = no smoke, fully hot = no smoke.
 




MistahYebba

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And the constant massive amount of coolant loss, plus the strong smell of syrup when the heat is on tells me there is most certainly a leak, probably related to the heating system.

But as Nate said, I can't see this leak causing smoke unless it's leaking on something hot.

But if it was leaking on something hot, how could it only leak on something hot when it is turned on half heat?

So lots of variables that make possible solutions sound unlikely.
 




MistahYebba

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Nate, if this changes anything...

I think this is what is happening. With the AC running, the smoke is (theoretically) building up while I drive. Therefore, after a 5-10 minute drive, sliding the temp control over from "cold" to right in the middle ("warm"), some part in the air system now has an access point to release the smoke that was being built up... through the vents and into the cabin. Somehow, turning up the heat a little higher makes that access point no longer there.

What I DID notice that is a good variable to throw out there is... you know how you can PRESS the fan control knob to turn on and off the AC? Well.... I noticed that if the AC is OFF... I don't think the smoke is accumulating to be released when I turn the temp control to "medium".

in other words, the smoke (which would come through the vent should I choose to turn the temp control to medium) is only building up if the AC is turned ON.

This is just a theory and will require more trial and error, but does that change any of your ideas?
 




natenkiki2004

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Doesn't really change my thoughts on it. The tests I outlined in my first reply are what I'd do.

I also don't have AC so I can't really comment on that. Might be that you're leaking refrigerant? To me, that would be more likely, it has potential to get onto the blower motor resistor and burn off.
 




Jason94sport

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A new blower motor resister & a new heater core are cheap & easy to DIY replace. Buy both parts & just replace. Under $50
 




96EXXLTinCO

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oldmodman

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I have to do the same job on my 92.

Got the resistor pack, the new blower motor with cage, and the plug that goes into the resistors. The old plug was partially melted from the heat.

Total price for everything at Rock Auto was right at $60.00

So I looked around for other stuff I should get at the same time. I ordered the little plastic rollers for the window motor repair and the door latch plastic rollers.
A word of warning if you need the plastic covers for the locking pins. The kit of plastic sleeves are not the correct ones. Get the entire latch assembly. It's called the door lock striker kit. The plastic sleeves in the door lock striker anti rattle kit don't fit the doors.

Not to my problem. The very thin hard plastic vac lines are so old they have all cracked. These are the ones that go from the intake manifold to the vac canister(also hard black plastic), to the under side of the dash to the AC switch manifold door assembly. Does that have to come directly from Ford?
 




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