AC Compressor not receiving power

[bimmerR75]

Out of nowhere (as it usually occurs) my AC compressor has stopped working on my 1991 325i. As of right now, the clutch is not engaging. When i press the AC button on the idle speed changes (as if it was working), but the compressor clutch does not respond. Checked the voltage on electrical connection that goes to the compressor and got 0.0v, checked the voltage then on low-pressure switch on the receiver drier and also got 0.0v.

System was working fine 2 days ago, blowing cold air, clicking when the A/C clutch was engaged, but now I have nothing. Going to bring it by somewhere to have them check if there is refrigerant in it (which it should have, since I don't have gauges) since I read somewhere that if there is none, there would be no power that runs to either of those switches....

Any suggestions on where else to troubleshoot?

[bimmerR75]

To add an additional note. When engaging the AC button, the auxiliary fan also turns on.

[Mook613]

Suspect it to be your Evap Temp Sensor (regulator) or the A/C relay (6-prong) behind your dash. Likely to the be the temp sensor.
I'm actually having the same problem right now.

[bimmerR75]

Suspect it to be your Evap Temp Sensor (regulator) or the A/C relay (6-prong) behind your dash. Likely to the be the temp sensor.
I'm actually having the same problem right now.

After looking at a wiring diagram, given I am not receiving any volts in either plug, the next "relay" point would be power from the ETR. Do you happen to know what the resistance should be on the ETR? Going to try and pull it to check tomorrow. Hope its not that, but it seems like the only logical explanation given the AC Select Switch tuns the aux fan/raised idle on, but no power to dryer or compressor.

Is this a common issue?

[bimmerR75]

So got to the bottom of the problem, should have checked this in the first place. System has no charge. Tried putting some refrigerant in, clutch started spinning but then started spewing refrigerant out.

Something is up with the compressor. Hope it would just be the o-rings or something and not have to replace the whole thing.

[Mook613]

You may want to look into how you are checking your wiring. If you are getting 0v going into your LP switch then you won't be getting anything coming out of it either.

[bimmerR75]

You may want to look into how you are checking your wiring. If you are getting 0v going into your LP switch then you won't be getting anything coming out of it either.

Was checking with the engine on and AC selector switch in. I might be wrong, but given there is no freon/pressure in the system, doesn't both switches turn to open? Once there is pressue I think I would get a current.

Either way, compressor is jacked. Gotta find a used one or suck it up and purchase a new one unless there is a way to fix it.

[Mook613]

Late model cars should have a hi/low pressure switch. That switch is what kills power if refrigerant levels are too low or too high. If you aren't getting power after that switch then check refrigerant. If you aren't getting power to that switch then you have another problem further up the line.
I think older cars had a separate low and high switch.

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[Mook613]

And check rock auto for remanufactured compressors. That's where I got mine from, but not sure if it even works because I haven't gotten around to installing the Evap temp sensor.

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[bimmerR75]

So did some more research but now I am super confused. I am running the OEM AC Compressor (Part #6452 1386 464) and since Ive had the car, it was filled, and running with R134a, but upon inspection at some used parts online, it says it should be running R12.

All my lines have been retrofitted with the R134a adaptors, and it was working fine till last week. My thought is its just an old compressor (26+ years) but does that make sense for it to be running R134a?

Just concerned as I don't want to buy a new compressor and deal with this all over again.

Found this compressor, it was on their own website but its cheaper via ebay, it is identical to the one I have in the car right now:

http://www.ebay.com/itm/Remanufactured-Genuine-OEM-AC-Compressor-A-C-Clutch-For-BMW-3-5-7-Series-/291745353466?hash=item43ed60cefa:g:88MAAOSwXeJYIhtz&vxp=mtr

[Mook613]

Use the search function and find the detailed ac write up.
These cars were originally r-12, which is now illegal.

Three different compressors were used on the e30, so you need to find which one you have so that you order the right model to fit your already installed lines and bracket.
Any compressor you buy now will work with R134.

Recommended to replace at least the condenser with a parallel flow design as r134 is not as efficient as r12 so you'll want a better condenser to compensate.

Another thing is that you'll want to put a new drier in when opening the system.

AC can be a little confusing at first, but do some searching and you'll figure it out.

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[Mook613]

Refrigerant doesn't 'spew' out. You're likely seeing the oil coming out. Shaft seals go on these after a while. Repairing those seals is an option, but if it's am original compressor your shaft likely is too pitted to bother repairing anyways.

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[bimmerR75]

Refrigerant doesn't 'spew' out. You're likely seeing the oil coming out. Shaft seals go on these after a while. Repairing those seals is an option, but if it's am original compressor your shaft likely is too pitted to bother repairing anyways.

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Got it, the system wouldn't hold pressure for longer than a few minutes or so. I purchased some refridgerant with the UV dye to double check everything. Its more than likely oil mixed with refrigerant then thats leaking, theres a large wet spot under the compressor, but going to check with the dye before I replace everything.

Such a pain haha

[bimmerR75]

Mook, think you are right about the shaft seals. Would prefer to do that as a fix if possible to keep cost down. Ran the UV test and heres what I ended up with

This photo is from above the compressor, I ran a whole can of UV refrigerant through to get the full view:


And this is the front pulley/clutch area, couldn't get a photo of the clutch but the clutch was covered in UV dye. Is it fairly simple to find the shaft seal kit for the Seiko Seiki compressors?

[Mook613]

Photos don't work.

I had a big leak out of the compressor shaft seal and was looking into a rebuild. Ended up getting a remanufactured unit for about $250 and preferred that to trying the rebuild. I recall seeing some rebuild kits for about $75-$80, but it looked somewhat challenging and not a guaranteed fix as the shaft needs to be in good shape for the seals to work.

You may have more than one leak, but without the system having pressure you won't see where the other leaks are.
I thought I only had a compressor leak but then when the system built up the pressure we found that my condenser was hit by something and had a nice hole in it.

A/C can be a costly thing to get back running properly.

I've spent about CAN$1,500 at this point having the retrofit done (but that's quite a bit of labour included as I didn't want to bother with doing A/C work myself).
My A/C still doesn't work, but it's holding pressure and just has a electrical problem (the evap sensor which I noted above).