Tamas Debreczeni

I had my 550i for over a year now.

Lately my AC is acting weird. It stops working (gradually) after a couple hours of driving, totally random.

Recent experience: was driving from Key West to Miami (3.5 h drive), halfway the AC stopped blowing cold air. It did not stop all of the sudden, but kept blowing warmer and warmer air. Turned the AC off for 15 minutes, then back on. Everything worked fine for the rest of the way. On my way back the AC didn't turn off at all. Blew cold air.
This was the third time it has done this.

Took her to the local repair shop. The guy kept the car there the whole day , but there were busy.
When I finally called, he said "it's the compressor", but I am not convinced that he even took a hard look.
So before dropping the $1600 (900! for the compressor + 700 labor), I would really like to hear some feedback from the community. Any way to check if it's the compressor? Does anyone know an AC expert in a 50 mi radius around Miami?
Did a lot of research and I have nightmares with this photo I found on the forum with the whole car ripped to pieces, because of the evaporator.

NewBchnic

Id go to a parts store and buy a 20$ can of freon first, they will noramlly add it for you if you dont want to do it
Hopefully that will fix it, not sure but these cars in particule but low freon can sometimes make compressor act up, or wont blow cold even if the compressor engages

worth spending 20$ to check before any other options imo

FormerE30Owner

+1 On the freon top-up. Low freon can cause the expansion valve and exchanger to freeze up and the result is as you described. When you turn the system off, the ice melts and the system can work again until the nexr freeze up. Its worth a try.

Tamas Debreczeni

Will give it a try when I get home from Vacation. Will let you know.
Thank you for the input!

audiophool

Too much refrigerant can be bad for your system. I'd be trying to find a specialist. Or, gasp, the stealer. Ideally, the AC system needs to be evacuated and the removed refrigerant weighed to see if it's out of spec. If low, there's a leak. And it could well be the compressor - but I'd want a specialist to diagnose, not an overwhelmed indy I didn't trust.

KyleB

+1, before you blindly dump refrigerant into the AC system, you want to check for leak. What I used to do is fully evacuate the system with an AC machine, then I'd see if the system could hold vacuum for a few hours. If it'll hold vacuum, it'll hold pressure and that should confirm the lack of a leak.

good luck.

audiophool

If the evaporator froze, you'd lose airflow, not have the air get warmer and warmer as the core would be plugged with frost.

FormerE30Owner

Since we don't know what the air flows are, nor the exact temperature, we can't rule out a frozen evaporator.
Usually the freon kits have pressure gauges to enable one to know if one is over filling the system, so adding a bit shouldn't pose particular problems. If there is a leak, but isn't a large one, then topping up will restore system function for a while and also confirm the leak by losing capacity again.

Salut, Bob p.

FormerE30Owner

Not necessarily. Vacuum is only 15 psia at best, while the freon system works at over 100 psia, so holding vacuum doesn't mean that it will hold 100+ psia.

Salut, Bob P.

KyleB

vacuum is measured in in/hg, not psi.

a good AC machine can achieve more than 15 in/hg of vacuum. I never had a car come back with an AC leak doing it the way I did.

OP, BMW A/C systems use a fairly small amount of R134a. overfilling can sometimes be worse than underfilling. I would recommend taking your car to a shop with a proper AC machine. have them put the system under vacuum, record the vacuum level, and let it sit overnight. if it will hold vacuum overnight then it should hold pressure, and you can rule out a leak.

you can either do that, or do a quick evac and recharge and add some tracer dye to the system. you can then use a UV light to check for leaks. the only problem with this method is that you can't use a UV light to check for leaks at the evaporator. that picture you posted is of a car having the evaporator replaced, and yes it basically requires a full dismantling of your interior to access it.

either method is better than using the AC top off cans that you get at walmart, unless you have a proper set of AC gauges and can monitor high side and low side pressures.

having said all of that, I'm not so sure you have a leak. the symptoms you're describing aren't really consistent with a leak. I wouldn't be surprised if it was the compressor. E60 uses a clutchless variable displacement compressor, and they are known for getting 'lazy' over time and need replacement. id still take the normal steps to check for leaks first, its cheap and easy.

good luck.