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White smoke from AC area of engine bay

18K views 8 replies 6 participants last post by  balance 
#1 ·
My 740Li has begun to have a strange smoke coming from it. I have found that the white smoke, with a unique smell to it, was coming from the area where the AC compressor is located. It stopped spitting white smoke when I turned off the AC.

I looked under the car and the compressor appears to be fine. No noise or shaft play. There was a thin bit of oil on the bottom of the compressor, I assume from the release of coolant from the compressor.

My question is, what can cause this to happen?

Is it a seal, was it over pressurized, did the hose get a split and when the pressure gets too high it is releasing?

I believe it is a seal or a hose, but wanted to get the collective input from the 200 IQ found on this site!

Thanks for your thoughts. :thumbup:
 
#2 ·
Well if it was a leak of refrigerant, the vapors are going to apear white. But a leak of that size would probably happen unoticeably with system failure. Does the AC compressor still engauge with the AC running?

I have oil on my compressor but it's from leaking return hoses on my power steering.

Oh and so if it was a seal, they tipically leak slowly. Same with leaking hoses.
 
#3 ·
thanks

I agree that it is a large cloud. The compressor does engage. It is still being blowing cold inside the car. I have not checked high and low side yet.

Next step is to put in some dye and see where the dye comes out. That should help it.

I appreciate your help. Thanks.
 
#4 ·
Have you not had to put any refrigerant in so far to keep it cold? I'd like to see exactly what you're talking about though. If not a refrigerant leak, I wonder if the clutch is what is causing the smoke? Like if it wasn't engauging completely.
 
#5 ·
I had an 02 525i that did this exact same thing, even the smell! I since sold the car, but I never did find out what it was. The air was cold inside still. As soon as I would start smelling the odor, Id shut it off. I noticed that at highway speeds it was fine, no smell or anything. In stop and go traffic, Id start smelling it again. Sorry I couldnt be of any help :dunno:
 
#6 ·
Hi folks,

Any luck or word on this? I have the same thing happening. I hear a strange whirling sound along with the sweet smell at which point shortly after a puff of white smoke appears. If I turn the AC off just when I hear the whirling sound or the sweet smell, I can avoid the puff of smoke. Also it doesn't happen all the time (the strange sound and smell). I've gone as far as to run my car with the AC and the hood up in hopes of catching a picture of where the smoke is coming from - but no luck, nothing happens. Go figure.
 
#9 ·
Do all of these smoke issues happen in hot weather? I don't know much about A/C systems, but if these cars have a high pressure blowout valve in the A/C system, and the fan on the condensor is not getting the freon cool enough, you will have very high pressure in the system looking for the easiest way out, whether it is from a rubber seal, or a blowout valve.

If I were you guys, I'd go to a shop that does A/C work and put UV die in the system, then when it blows out again, the shop can look and see exactly where it is coming from with a UV flashlight.
 
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