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WARNING!! Sudden loss of A/C and Burning smell (archive)

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Posted by John R Brandl on October 19, 2001 at 20:00:16:

My wife was driving our 89 535i yesterday and the A/C stopped blowing cold and a smell of burning plastic came into the car. She was two blocks from home and she shut off the A/C and pulled into our driveway. Today I checked to see what is going on. Turn on car and press snowflake and the aux fan comes on but no engagement of the compressor.
I checked all fuses and relays and all were good. I thought I was low on freon and the low pressure switch kicked in but it was full of freon and all looked well at the drier.
I then looked at compressor and clutch and all looked OK.
I then removed Air cleaner assembly and looked for the connection from the car to the compressor and found the wires burnt and melted. The reason for this??????
Two years ago my BMW dealer replaced my compressor and the overzealous mechanic tie wrapped the two sets of wires that come from the compressor to the harness so they wouldn't rub on anything. That would have been fine if he wouldn't have tightend the tie wraps so tight that they actually compressed the wires and at the one that was the tightest it took two years of heat in those wires for them to short out and burn. Thank God the 12V wire, the black one, burned in two instead of continuing to melt and start a fire.
I will head to the auto parts store for some new wires and connectors tomorrow. By the way this also melted the foam insulation over the low pressure hose leading back to the compressor.
Moral of the story: Tie wraps are good, but do not over tighten.

John Brandl 1989 535i 5 speed BMWCCA

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