Freon shot out of my car while driving... A/C stopped working... Advice?

[rmz]

While driving down the street the freon in my AC system shot out from somewhere under the hood and AC stopped working. Apparently this happened once before while at idle and parked when my brother borrowed my car but the AC still worked fine after.

Looking under the hood I didn't see any clear indication of where it came from... I hooked up my manifold to it and the high side pressure was 0 even though the compressor did come on and the low side pressure was 25-30.

compressor still turns on when i turn on the AC, which I don't understand... but the AC does not blow cold.

So has anyone else had any problem like this? Do our cars have a pressure release valve that could have gone bad? If so, where is it? Any advice on what to do? I don't know much about AC other than how to check the pressure and recharge a working system... so there could definitely be a lot I am missing.

[kapone]

Your system dumped the freon, because the pressure built up higher than it's supposed to, most probably due to heat and the reason for THAT is probably because your Aux fan stopped working, and it's been real hot lately.

Have you checked your Aux fan recently?

[rmz]

Your system dumped the freon, because the pressure built up higher than it's supposed to, most probably due to heat and the reason for THAT is probably because your Aux fan stopped working, and it's been real hot lately.

Have you checked your Aux fan recently?

damn! that's good thinking! thanks!

I have not checked it, I'll make sure it's working... it was very hot when this happened. I guess I should also check to make sure my condensor and radiator are not all full of road gunk... I have seen this be a problem for radiators making car overheat... I guess it could also be a problem for AC.

For anyone who knows about AC systems:
-Why is my compressor still turning on? doesn't it require 40psi or something to turn on? does this mean it has at least 40psi? high side gauge said 0...
-before refilling it (I have big tank of freon) do I really need to vacuum it out? or should I just add freon till the gauges show it is within range?

[Edwin NL]

Did you fill it yourself?

Aux fan not working will not cause the system to dump, to high pressure can.

[rmz]

Edwin:

I did not charge it myself... I hadn't touche the AC system since I bought the car.

Should the system dump freon into the cannister instead of the atmosphere? if so does the fact that it shot out of the car mean I have a leak somewhere for sure?

I did not do anything to it yet... looking for advice before I do.

[Edwin NL]

Were did it blow/dump? could just be that you sprung a leak.

[rmz]

Were did it blow/dump? could just be that you sprung a leak.

thats what i am afraid of... but before looking for it (which i have no experience doing) or paying someone else to find the leak, i was wondering if there is any pressure release valve who's operation i can check or if this has happened to other e38 owners and what the common causes were.

[redpicker]

One thing I can assure you; if you just fill the system with more freon, you will be replacing the compressor in the near future. The oil that lubricates the compressor is mixed with the freon. A large freon leak is also an oil leak.

You need to find out why it lost the freon. You said it happened before--did your brother find out why it happened? What did you do to correct that problem?

Just from what you have reported, it would appear that either the person reading the gauges is not doing that correctly, or your system is seriously fubar'ed

rp

[Edwin NL]

Shops can add a leak solution to the freon and oil so when it blows it leaves a green residue

[DenisMcG]

Did you fill it yourself?

Aux fan not working will not cause the system to dump, to high pressure can.

If the aux fan is not working, the temp through the condensor will get too high, and in turn will cause the pressure to climb rapidly and blow the coolant out of the high pressure relief valve.

Make sure the aux fan is working prior to refilling.

[bumse60]

If the aux fan is not working, the temp through the condensor will get too high, and in turn will cause the pressure to climb rapidly and blow the coolant out of the high pressure relief valve.

Make sure the aux fan is working prior to refilling.


I was told by the A/C specialist that this is exactly what happened to me.

The pressure sensor (pos 4):

http://www.realoem.com/bmw/showparts.do?model=GG81&mospid=47517&btnr=64_0620&hg=64&fg=60

was bad causing the aux fan not to start when pressure was building in the system. The aux fan itself was not faulty so it started alright when required by engine temperature which made the fault tracing a bit confusing.

Note that aux fan control is different between earlier and later E38s, where earlier seem to have two speed fans and later PWM controlled. So this exact fault may not apply to your car but I still think a faulty aux fan may cause the A/C system to dump refrigigant due to too high pressure.

[Edwin NL]

I think half of the E38 owners don't have the aux fan working, I know a few that have been driving around for about 2 years and no issue at all besides lower AC power when idle.

The aux fan only comes on at idle when the car has no road wind.

[bumse60]

The aux fan only comes on at idle when the car has no road wind.

Since I had troubles with this recently I looked up the description of the pressure sensor function in WDS (this only applies to E38 after 09/98):

According to the description the aux fan may run if vehicle speed is under 80 km/h.

There are 16 speeds (numbered from 0 to 15) where speed 0 corresponds to 8 bar pressure, speed 1 to 9 bar pressure and so on up to speed 15 that kicks in when the pressure is >24 bar.

However, my experience is also that the A/C will function even if the aux fan is not running even when standing still.

The problem in my case was that the compressor was starting to make a noise. Two compressors were changed before the faulty pressure sensor was discovered...

[sneakysneaky]

pressure is def off...why dont you evacuate the system and see what kind of vacuum it'll pull....should be close to 30...if it pulls a good vacuum recharge and then test those fans...make sense that it happened at idle and not when you were moving. should be an easy fix.

[audiavant]

i have the exact same problem. My aux fan/compressor/clutch are all working fine so Im heading towards the receiver-dryer as the culprit. Will let you know. BTW...be thankful the check-valve is doing its job...........I am

[Pedro Rabie]

There's also an auxiliary fan for the AC???

What's next? A supporting schock absorber? A preliminary heat dissipator? A preemptive fuel accelerator??

Oh G. This car is plenty of gadgets awaiting to fail.

Pedro:rolleyes

[amschnellsten]

The Aux fan should kick on when the AC is on. You will loose refrigerant if your AC system overheats, the pressure relief vavle will release enough until it is safe. If you did not know there are specs to fill an Ac system. The psi in the lines is on a scale with temperature. I would suggest vacuuming it out, adding oil, and refilling. If you do not have a vacuum, Harbor Freight sells one really cheap.

[rmz]

Thank you all!!! Problem identified!!!

My aux fan was culprit. I took it to the shop I used to work at and we sucked out the system and made sure no leaks... It held vacuum and so we charged it the right way adding oil and all with the big old snap on machine.

Held pressure fine, ac worked fine but when sitting parked aux fan would not come on and pressure kept climbing till we hosed down the condensor and it went back down to normal for a bit.

After closer examination on a lift, was clear that freon had shot out from pressure release valve. There was a faint trail there.

Ac now works great when driving at high speeds... Still won't let I run when I'm in traffic or stopped. Going to replace the aux fan now and see what happens. I will definitely keep you guys posted.

Note: fan was getting voltage. I don't know how long ago fan failed... But on hot day it was just too much. Probably exacerbated by fact that I always have it on 60 degree setting.