heater = smoke under the hood!

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slofut
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heater = smoke under the hood!

Post by slofut »

Cooled off a bit today. So I decided to see if the heater worked on this car, I've never turned it on before. Pushed the air cond button off, the blower in the dash stopped. Slid the sliders to floor, and turned the fan control all the way to max since it wasn't blowing. I noticed when I reached the very end of the fan control, the idle speed would drop. So I left the blower knob on max and popped the hood to see if the AC compressor was coming on in this mode, it wasn't, and then there was smoke pouring out of the cowl!!
Turned off the blower control, smoke stopped but the sick feeling still hasn't...
Any ideas? Is there a seperate blower for the heater and is it under the hood beneath that metal cover? And I'll bet it comes out via the footwells inside the car?

Dammit, I'm sick... Your thought's would be appreciated.
Bill
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hornhospital
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Post by hornhospital »

You figured it out. The fan for a heater (separate from the AC fan) is under the metal cover in the cowl area, and undoubtedly something obstructed it's rotation, or the bearings were seized when you switched it on. It sat there trying to turn until it cooked the windings. You let the magical smoke out of the windings. It's unlikely it will ever work again, since it's almost impossible to replace the smoke. You have to get new wires with the smoke still in it for it to run again.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
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Post by Erik_M6 »

Sounds like the blower motor has turned for the last time and just bound up. Can be R&R'ed from the outside, removing a couple of covers in the center of the firewall area, aft of the engine and at the base of the windscreen.
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1988 M6 - Track
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slofut
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Post by slofut »

Hey guys, you are correct, thanks much!
The blower motor was tight and wouldn't rotate. After tweeking around with it, it freed up, so I oiled it up with an electrical spray (corrosionX) and it fired right up and ran again again until it came to a halt. So I pulled it out, (piece o cake) and am looking at a replacement motor on the bay. There's a new bosch one with a part number ending in 013 instead of 012, looks identical. Do you know if the 013 part is interchangable? I remember reading a thread a while back that someone interchanged heat and AC blowers with no ill effects.
Your help is appreciated, and I'm happy my car isn't fried!
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hornhospital
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Post by hornhospital »

Bill, you could check Realoem.com to see if the numbers interchange. Sometimes they'll have a discontinued number followed by "superceded by part number below".

I'm surprised the fuse didn't blow while letting out all that smoke.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
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slofut
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Post by slofut »

hornhospital wrote:Bill, you could check Realoem.com to see if the numbers interchange. Sometimes they'll have a discontinued number followed by "superceded by part number below".

I'm surprised the fuse didn't blow while letting out all that smoke.
Yea me too Ken, it smoked pretty good, but the wires to the transistor and the wires to the motor are all fine. I expected the worst. looks like the heat was in the motor case. No fuse blown? Seems pretty dangerous to me. I'll look at the fuse later just to see what it looks like, I'd expect a 20amp, or even a 30? do you know which fuse it is off hand?

I'll go check realoem.
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Post by hornhospital »

Fuse 14, should be 25 amp.
Ken Kanne
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Post by slofut »

hornhospital wrote:Fuse 14, should be 25 amp.
Thanks much Ken. This helps when time is limited.
Bill
BenM635i
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Re: heater = smoke under the hood!

Post by BenM635i »

thread revival... i also have magic smoke :)

Got the car out for a decent drive today in preparation for MOT at some point over the coming weeks. All checks out fine and dandy however heater was screeching a little.

I switched the heater off then back on again, seemed ok. As parked up though no heater and puffs of magic smelly smoke from the heater motor area.

2 questions, first is fuse.. it didnt blow so has anyone got a definitive fuse number for the blower for an M6 '84? Will take the fuse out before i use the car again just to be on the safe side, dont want to start smoking in the MOT station!

2nd, ill strip the motor out tomorrow but sure its replacement time - part number 64111354618 as per realoem. Anyone know where to pick up a replacement motor?

Cheapest i can find in uk is: https://www.buycarparts.co.uk/magneti-marelli/7062762 ... £179

Seems i might have to get the wallet out.
'85 M635 #160
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sharkfan
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Re: heater = smoke under the hood!

Post by sharkfan »

The main ventilation blower on an E24 is something I've considered an annual maintenance item for many years now, along with rear light removal and clean, throttle body springs, links and cable lubrication, gummi-plefge of all the rubber seals etc, etc.

Getting to the motor to clean and lubricate the bearings is very easy and worthwhile doing every spring to also clean out any crap in the scuttle area.

My two cars ventilation motors have survived for years on a few minutes clean and grease.
2001 Alpina B10 V8 Touring (1 of 12 rhd)
1997 Alpina B12 5.7 L (1 of 2 rhd)
1995 Alpina B10 4.6 Touring (1 of 1 rhd)
1985 BMW M635CSi (1 of 524 rhd)
1982 BMW 635CSiA (1 of 100's left from the 1000's made and still valiantly fighting against a rusty grave)
BenM635i
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Re: heater = smoke under the hood!

Post by BenM635i »

Yep, kicking myself now as i had the scuttle off a year ago anyway while doing some OBC / alarm related stuff - just didnt service the motor while there. My mistake but lesson learnt.

edit: Just got the old motor out, very stiff however a session of lube out of a can and it runs perfectly, going to leave it to soak overnight in penetrating oil then grease then its good to go.

However :( both the AC + Heater motor only run on full ... the dial does nowt until i switch it to maximum. As per the font of knowledge that is bigcoupe:

viewtopic.php?t=14791&

Looks like its time to repair the transitor in the dash. Jammed motor must have burnt it out, silly old me ;)

Good news is that i dont need a blower motor, bad news is the repair looks a bit more complex than just bolting a new motor in.

Moral of the story, lube that blower motor!
'85 M635 #160
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