Measuring compressor clutch voltage
 

Hi,
My clutch is not turning and I like to find out if it need to be replaced or not. Today I measured the voltage feeding to clutch and it was 4.8v instead of 12v or 0 that I expected. I am not sure if I am measuring it at the right location. The picture shows where I am measuring it.

I appreciate if someone could explain to me why the voltage reading is like this.

Thanks

That looks like the clutch connector to me. One wire in a circular connector.
Make sure you have a good ground somewhere nearby.

Which model AC compressor do you have? It doesn't look like my Denso.

You may want to read this linky...

http://www.justanswer.com/bmw/5aldt-...html#re.v/174/

You can also try to measure clutch coil resistance and/or supply 12V directly to the coil connector and see if clutch engage. I would recommend to visually inspect clutch for mechanical damage and try to spin compressor by hand before attempting any other repair technique. I had broken thermal fuse on my 2003 3.0 which I successfully bypassed two years ago. Still works great. You may read how I did it in this thread, beginning at post #4.

http://www.xoutpost.com/bmw-sav-foru...placeable.html

He probably have the variable clutchless compressor. 5 volts is the correct voltage for that model.

Calsonic Kansei

I can turn clutch with my hand. Here is what it looks like.

My A.C has been blowing warm air for last two years. It stopped when car was idle with a bang and burnet plastic smell that I could not figure from where it was coming.

So to test with 12v, can I simply connect battery terminal to round connector on top of compressor?

Interesting. My is same year and failed around same mileage. Going strong today with bypassed thermal fuse.

If you read my and some other posters, 5 volts is the correct voltage. Putting 12 volts to that terminal is just going to fry some delicate electronic components.

Better to take it in if you don't know what you are doing, rather then risk damaging more parts.