A/C has no freon at idle.

[Ariel525i]

Hi everyone.

The air conditioner of my '89 525i M/T ,for the past weeks has been blowing out air without freon when idling. When the car is running wherein revs are past 1.5 rpm(or normal driving) there is cool air coming out of the vents. It only seems to cut the compressor when at idle. Aside from that, occasionally there is a smell of "rotten eggs" coming out from the vents, and the vents of the whole left side of the car suddenly blow out warm air while the right side blows out normal cool air. Im not sure if these things I am experiencing are all inter related or they are seperate cases of problems.

Anybody out there experienced these as well?

Thanks in advance.

[632 Regal]

no

[dacoyote]

no

same here...

[calmloki]

I'm thinking that the no cool at low rpm is a possible indicator of the electric fan not working - thinking that you are only doing higher rpms while driving, thus forcing air through the condensor. Check through the grill to see if the fan is spinning. Rotten egg smell = sulphur, common to human or car farts. Assuming you aren't farting in your car there could be an over-rich condition causing your catalytic converter to be working and stinking up the place. My guess is that you aren't really smelling sulphur, but that the AC evaporator has a nice moldy stinky coating. Replace your cabin filter lately? There's a product designed to kill the stuff that's stinking, but I wouldn't use it without pulling the filter. Sudden one side heat sounds like a bad heater valve or heater valve switch (driver/passenger climate control) for the driver's side doesn't it? Or do both sides fail together?
Tom Walrod

[632 Regal]

his car dont have a microfilter but still could be real moldy.

[SRR2]

This is a common affliction among early E34s lacking the microfilter. Crud of all description works its way into the intake side of the evaporator and a) blocks it, and b) rots. The former causes the a/c to short-cycle, the latter stinks. The short cycling is caused by the lack of air over the evaporator. It cools down very quickly and the thermostat cuts off the compressor. When I had my E34 this problem occurred yearly thanks to locust trees and mice.

Before you do anything else, you will have to disassemble the blower access panel in the center of the firewall. Bentley has minimal instructions. If you search for E34 blower replacement (or words to that effect), you can find others. It's not a particularly fun job because it involves removal of a number of hoses and wiring, and the coolant tank, which means removing coolant. But it's a do-able job. You will probably need to remove the blower to clean out the evaporator completely. While you're at it, consider inspecting and possibly replacing the blower motor brushes. I believe there's something on this in the archives here.

I've had pretty good success cleaning and deodorizing the evaporator in the presence of residue from seriously decayed material using a portable steam cleaner. It basically melts the gunk away, sterlizes the metal, and doesn't produce a high volume of condensed water so that it overruns the drain. It's safe to use with R-12 since the temperature of the steam is far below the decomposition temperature of the refrigerant.