Need help with AC in my 1990 535i

[BlueAngel]

I just had a rebuilt AC compressor installed in my 1990 535i and its not blowing the cold air expected. Mechanic says its fine, but I had doubts. I took it to my friends dad who used to do AC's and he installed a digital temp gauge in the vent. We got an average reading of 59-61 degrees which he says is not normal and should read somewhere in the 40's. I also noticed it only gets cooler when i'm driving. Temperature drops to like 52-53 degrees while driving, whats that about? My friends dad thinks theres air still in the system and not enough freon was put in.What should be the proper temperature? Thanks in advance

Nik

I'm going to push this back up and see if I can get someone to help me out with this AC problem. This is a problem I have been having since I bought this "abortion" about a year ago. This car has been my own personal recession. Just throwing money into it. I bought an AC compressor about a year ago from the classifieds here and it only lasted a week and now that I finally located a rebuilt one, it still doesnt work properly. I am giving this car one more summer and will get rid of it once and for all. I will never buy an old BMW again. Parts are very hard to find and its hard to find a mechanic who knows what hes doing without him robbing you.

[Derek A.]

Does the aux fan come on when you turn on the A/C ?

[Sneezy]

That. Check fan first. If the fan is working prepare to throw more money at it.

It's a 25yo sport sedan, dude. It runs on cash.

[70383roadrunner]

My 89 535i only gets down to around 50 degrees with R134 conversion. With 12 it would freeze you out! I have no use for R134. Bring back R12!

[cooperman]

If you put R134a in it, you probably have a normally functioning car. These AC systems were sized for R12. My AC had been converted to R134a and worked as yours does now. I switched back to R12 and now it blows very cold.

If you work on the system, make sure it is vaccumed completely and that you replaced the dryer. Do not just keep putting refrigerant in hoping it will blow colder. If you overfill it, it will actually cause it to function wose than if it is slightly underfilled. Check your Bentley manual for capacity (R12 is a little over 4 lbs.). Good luck.

[70383roadrunner]

If you put R134a in it, you probably have a normally functioning car. These AC systems were sized for R12. My AC had been converted to R134a and worked as yours does now. I switched back to R12 and now it blows very cold.

If you work on the system, make sure it is vaccumed completely and that you replaced the dryer. Do not just keep putting refrigerant in hoping it will blow colder. If you overfill it, it will actually cause it to function wose than if it is slightly underfilled. Check your Bentley manual for capacity (R12 is a little over 4 lbs.). Good luck.


The sticker that BMW put on after the conversion says 2.09 lbs R134. Doesn't seem like much!

[3axap]

My guess is that the system was not charged properly or there are issues somewhere that the mechanic didn't touch like the expansion valve, evaporator or condenser. I converted my R12 system to R134 when I installed a rebuilt compressor. In the hot Florida summer my A/C reaches 42-46 degrees when stopped and as low as 38 degrees when moving. Yes, R134 is not as great as R12, but its not a drastic difference. Your mileage may vary based on how thoroughly the system was inspected and repaired as well as how knowledgeable your mechanic is when it comes to A/C work. My advice for a resolution would be to put a proper gauge set and measure the low and high side pressures. Rev the engine with gauge attached to see if you draw the low side into a vacuum. That can indicate pluggage around the evaporator or expansion valve. Similarly, spiking high side readings can indicate restrictions in the condenser. Here's a good guide to A/C system pressure readings:
http://www.ackits.com/aacf/ptchart.cfm

[cooperman]

If you can get some gauges, your low side should read between 50 and 80 PSI and the high side between 150 and 210 PSI when the system is fully charged and running. With the system off, both gauges should read betweeen 75 and 100 PSI.

[BlueAngel]

Hello, gents! I didnt mean to be rude by not responding, but the instant email notification on this site doesnt work anymore.

Yes, the aux fan does come on and i'll check out the rest and try n update you gents, thanks so much for your kind help, u guys rock! :buttrock

Nik