Problem with A/C

[andrewwynn]

Originally Posted by X5chemist

The fan does not start up when I pull the sensor off the coolant line. So I guess my sensor is toast. Time to drain the coolant and replace it.

That's backwards. Pulling the pressure sensor from AC line will make the aux fan spin; indication of a problem with the fan not the AC.

Can you engage the fan with your scanner?

You said coolant line, do you mean refrigerant line? Pulling the radiator outlet line I'm not aware of having an effect on that

[daki50]

I was able to turn on the fan with the diagnostics


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[X5chemist]

Yes, I can manually activate the fan. Plus it takes 10+ seconds to spin down after turning it off when hot. I've not pull the refrigerant sensor off. Unlike others, it has to be emptied of R134. Luckily, I have the tools to do a R134 vac and fill.

[daki50]

Originally Posted by X5chemist

Yes, I can manually activate the fan. Plus it takes 10+ seconds to spin down after turning it off when hot. I've not pull the refrigerant sensor off. Unlike others, it has to be emptied of R134. Luckily, I have the tools to do a R134 vac and fill.

Try disconnecting the pressure sensor on the air conditioning pipe, you don't have to remove the sensor


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[Corellian Corvette]

Hey so I experienced this problem and found the issue searching other forums. I'll see if I can find those links, but bear with me.

BMW AC compressors of this era have a mechanical valve inside that can fail, and make diagnosing the problem impossible. The compressor clutch will turn on, but the AC will blow warm until you rev the engine. Because the system thinks the AC is working, you'll see a bunch of electrical anomalies since the pressures aren't what the system expects.

So if your problem is that the clutch is engaging, but you don't have cold air until/unless you rev the engine OR it takes a long time to cool off, this valve inside the compressor is bad and the compressor needs to be replaced.

Diagnosis of this problem is almost impossible since it's a physical valve inside the compressor so no error of this problem will show up in the scanner.

I'll see if I can find a link to the thread that explains this better. But long story short you need a new compressor.

[daki50]

Originally Posted by Corellian Corvette

Hey so I experienced this problem and found the issue searching other forums. I'll see if I can find those links, but bear with me.

BMW AC compressors of this era have a mechanical valve inside that can fail, and make diagnosing the problem impossible. The compressor clutch will turn on, but the AC will blow warm until you rev the engine. Because the system thinks the AC is working, you'll see a bunch of electrical anomalies since the pressures aren't what the system expects.

So if your problem is that the clutch is engaging, but you don't have cold air until/unless you rev the engine OR it takes a long time to cool off, this valve inside the compressor is bad and the compressor needs to be replaced.

Diagnosis of this problem is almost impossible since it's a physical valve inside the compressor so no error of this problem will show up in the scanner.

I'll see if I can find a link to the thread that explains this better. But long story short you need a new compressor.

It is not possible to replace the valve itself but the whole compressor has to?


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[Corellian Corvette]

So look up "variable stage compressor" that's what is in these cars.

No, when that goes bad the compressor needs to be replaced.

It took me a LONG time to track this down because this problem is really common and most forum suggestions are to do a ton of diagnosis. I wish I had saved the thread.

But if your problem is as I described (AC blowing warm but system is full and cools of when driving or revving the engine) then the variable valve is bad and the compressor is definitely the problem.

[daki50]

Originally Posted by Corellian Corvette

So look up "variable stage compressor" that's what is in these cars.

No, when that goes bad the compressor needs to be replaced.

It took me a LONG time to track this down because this problem is really common and most forum suggestions are to do a ton of diagnosis. I wish I had saved the thread.

But if your problem is as I described (AC blowing warm but system is full and cools of when driving or revving the engine) then the variable valve is bad and the compressor is definitely the problem.

My problem is this: The compressor and fan will not start until the engine reaches operating temperature and I do not give gas up to approximately 3000rpm once. And then everything works normally while the car is standing and driving


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[Corellian Corvette]

Same problem. I found the post and it was on this forum. It even describes your issue where the fan doesn't come on.

A bad valve will cause these problems as well. You can see the post here (post 6). Replace your compressor.

https://xoutpost.com/bmw-sav-forums/...tml#post879005

[daki50]

That could really be a problem, but I see on the internet that only that valve can be bought, I don't know if anyone did that here


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