Got a 92 Rs with white smoke coming out the dash vents. Seems to be smoking when the blower motor is on. Any likely culprits to look into?

Update: The smoke is coming from behind the HVAC control switches...

 

Smoke? Or steam? Does the smoke smell like burning or sweet like antifreeze? Do you get a head ache driving the car with the heat on and the windows up? Do the windows fog up? Short of the heater blower burning up, there isn't much in there that cause burning problems... The heater core can go bad, which will blow steamy antifreeze through the vent system.

You could run the fan and lightly touch the motor housing under the hood and see if it's hot. Usually they just stop blowing or they squeel like a banshee.

 

Its definitely smoke. I cant really describe the smell, but its definitely not antifreeze. Its a horrible smell thats all i can say.

Ive taken the radio bezel/cover plate off and you can see the smoke coming from behind the HVAC controls. About to remove it and see if anythings fried back there.

 

That's probably your best bet... It could be a light bulb up against something causing it to melt, or a wiring problem that's generating heat. The only way you'll really know is to disassembled and visually inspect the area.

 

Smoke is coming from this part. Any idea what its called?

 

Also this plug that connects into the AC/heater control relay is partially melted (The part/relay behind the **** you turn to control the blower speed). Do you guys think this could be causing the smoke? Bad relay???

 

Mode select switch, But looks like your building up heat so it maybe a bad blower motor as well or the blower resistor

 

Where's the blower resistor located? And so its a bad mode select switch, and/or a bad blower motor?

 

Before you jump a head does all the fan speeds work? like 1, 2, 3, 4? or do you only have one speed if so the your resistor is bad, its on the heater box next to the blower motor. But it could be a bad blower motor causing the problem, does it sound funny or loud? when on.

 

On top of the heater/AC box under the hood there's a plug with 4 or 5 wires, the piece it plugs into is the resistor pack. Remove the two screws and it'll lift out. There should be a couple wire coils, if they're broken or melted the resistor pack needs to be replaced.

The melted fan switch plug is most likely the source of your smoke. The switch itself could be the problem.

While you're under the hood, check out the hi speed fan relay, it's next to the blower motor on the heater box.

The heat is either from a shorted component, or dirty connections. Check the connections. You can probably find diagnostic charts and information in the service manual for your car, if you have access to one.

 

I don't mean to thread jack but this has happened to me...I thought it was just me so I kinda just ignore it....nothings burning or anything but what could cause it?

 

When a heater core goes bad, it'll let steaming antifreeze into the heater box and vents. Usually it's just a pinhole leak at first and you may not notice it. Sometimes it'll give you a head ache before it starts fogging up the inside of the windshield, or floods the carpet under the passengers side of the dash. It's just one possible symptom of a bad heater core. Exhaust leaks and bad seals in the engine compartment can have the same effect.

 

Ok I will test the fan speeds tomorrow and check out the resistor aswell. Will report back with my findings.


Its fine man, I don't mind.

 

All of the blower speeds seem to be fine, except for the medium speed; which seemed to work every other time. The resistor looks good, blower motor isnt making any weird noises, and the high speed relay looks fine.

I have a spare fan switch and mode select switch than I am going to put in. Is the melted fan switch plug going to be a problem though, will it still function correctly or do I need to replace the plug?

UPDATE; Went ahead and ordered a new plug just in case.

 

I am having this same problem in my 87 Iroc. First noticed a a small trail of smoke coming out of my AC vent in the middle top one by the dash pad. Today I had a bunch of smoke coming from behind my HVAC controls. That was the first time I had seen it coming from there. My dad seems to think it sounds like the heater core is bad but he has not had a chance to look at it he only knows what I have told him. He also asked me if it was a sweet smell but idk what he means by that... If I had to describe it sweet would not be on the list of words I would use. I told him is more of a nasty smell. And it definitely gives me a head ache when driving with the windows up I have to roll them down. Havent noticed any fog build up on my windshield. Did you ever find out what the issue was that was causing this?

 

I was also wondering do you have to be running your heater for your heater core to be causing this? I rarely use my AC or my heater for that matter. And I know for a fact the times I have noticed this I was not running either. Also even when there are no visual symptoms such as the smoke I described the horrid smell I described is still there and giving me head aches... Was hoping some one could help me try and figure this out.

Also have NOT noticed any puddles of water under the dash passenger side like my dad described to me said it was usually a symptom...

 

Its not the heater core, the sweet smell your dads referring to is what antifreeze smells like. Its very distinct.

Pull out your HVAC controls, and pull off the AC/Heater blower control switch connector. You'll probably find it partially melted like the pics I posted. I ended up replacing that switch, and the mode select switch. Haven't had a problem since.

 

Ok were going to be working on my car today ill mention it to my pops and try to have him help me take a look. He's kinda the brains but I want to learn. Thx Rich92 RS.

 

Anytime man. If you have any questions feel free to ask or make a thread, theres plenty of people here willing to help you learn.

 

Dont mean to jack this thread but there is alittle rubber elbow thats on the heaterbox, mine isn't connected at one end, what's this elbow for?

 

Thx a lot man. I know everyone on here has been really helpful. There is ton of info on this board at my finger tips. I have learned quite a bit already but I still have tons to learn. This board is awesome and there are a bunch a knowledgeable people I look forward to learning from. Thx again.

 

No idea. I think it lets cooler air from inside the HVAC box cool the blower motor??? Thats my best guess.

 

exhaust hose, suppose to let heat out of the blower motor, to prevent overheating...atleast thats wut i waz told

 

I've had this same problem on my 91 formula 350. i'm gonna check the blower motor and the resistor 1st, but I saw something about a possible exhaust leak? that kinda freaks me out. how would exhaust be getting into the vents? I noticed that it only seems to smoke noticeably when I'm really stepping on it, doesn't seem to smoke at all when it's just idling or cruising. my blower motor isn't working right, only one speed, so I'm hoping its simple as that. but any info on a possible exhaust leak would probably be good to know, just in case.