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Discussion Starter #1
Hello guys,

My AC quit working on me yesterday. It was blowing cold before and all the sudden it started to blow hot air.

Put a gauge on the system and it was showing 50PSI on the low side.

The clutch was engaging and the compressor itself was turning.

Crawled undernath the car and I saw that there was green goop leaking from the backside of the AC compressor?

With the car off I can also myself turn the compressor with my fingers si it not seized.

Does this confirm an AC compressor failure?

I happen to have a used spare AC compressor at home.

Anything special I need to know swapping the compressor on this car?

I read it's better to swap the drier at the same time.
 

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If You decide to replace compressor, dryer has to be replaced too. new o-rings and you better buy original bmw, they are more expensive but you don't want to face leak because of cheap o- ring. new hi- and low side valves. And you should flush your system in order to remove old dirty oil to protect your new compressor. Right compressor oil as per compressor's specification (usually mentioned in compressor leaflet). Proper vacuuming and filling with right amount of oil as per your car specification.
 

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Discussion Starter #3
This morning had a better look at the car. The leak on the compressor came from the pressure relief valve.

It seems somehow the pressure got too high in the high pressure side and the valve opened to relieve it.

I decided to do more testing before I start taking the system apart.

I recharged the system with a Freon/oil charge and the the ac blows cold again. HOWEVER my cars electric fan does not seem to come on when I turn the AC on. I don’t even know and did not notice until recently if it is supposed to come on when the ac is turned on. My gut tells me it should turn on to cool the condenser. Maybe this is the reason for blowing the high pressure side relief valve: high side runs hot then the pressure build up and blows the relief valve? Who knows...

With the fan not coming on I decided to only use the AC when the car is moving at speed. Drove the car 220 miles on the highway today and the ac was cold the whole way. Whenever I hit a traffic jam I turned the AC off to avoid problems. This workaround seems to do the trick for now.

Now I need to look into that electric fan some more.

My car does not have a mechanical fan, it only has one electric fan on the engine side of the radiator/ condenser

I let my car idle for a long time(with the ac off) andthe fan does come on when the cooling system gets warM enough. So the fan does work.

i wonder why it does not come on when the ac gets turned on.
 

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The engine computer (DME in BMWspeak) controls the fan via a thin wire in the fan’s harness. As the fan came on under other circumstances we can assume that the fan is ok. The problem could be in the DME. The DME and the climate control module (IHKA) communicate. The compressor clutch won’t be activated unless the DME says it’s ok to do so. Then the IHKA activates the clutch by activating a relay (see link for location and part #).


I’d PM Bali Dawg as he’s the DME expert.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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MM is correct, just thought I'dd add some information to further explain what he is trying to convey:

The primary fan (manual trans and not fan/fan clutch, in your case) behind the radiator is supposed to come on at various stages based upon two completely independent control systems. (The two can/will overlap)
If when the engine coolant temperature IN THE RADIATOR becomes too hot the fan will come on to cool off what's in the radiator.
The fan should also come on when the system pressure in the A/C system reaches XX pressure, in an effort to aid in condensing the R-134A from a hot gas back to a cooler liquid state.
Again both commands (DME controls) can be present at the same time.

Here's a couple of things for you to look at:

Notice the 15 different stages of the fan; all based upon A/C system pressure.


 
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