how to engage ac comnpressor

[e30moneypit]

so everything was working fine --- but slowly ac started losing its cooling. I was too lazy till today it stopped blowing cold air. Now compressor wont turn on . everything else works.... so its got to be low on freon.

now please tell me how to jump the compressor. pics would help.I understand teh compressor has to be on before i can feed it freon.

91 325i..... no hacks or anything previously done. was working 100% but slowly ran out of cold then cool .. now ambient air only.

[TobyB]

just hit the solenoid on the compressor with 12v-
on the '90, there's a 2- pole connector with only
1 wire in it.

Might be worth finding the leak, tho.

t

[LJK]

Don't keep trying to run it empty. It has a pressure sensor that can inhibit compressor operation above/below a certain pressure. That's why its off. It doesn't magically make things cool when engaged. It requires freon and proper lubrication.

[redsubdivisions]

Don't keep trying to run it empty. It has a pressure sensor that can inhibit compressor operation above/below a certain pressure. That's why its off. It doesn't magically make things cool when engaged. It requires freon and proper lubrication.

^^^^This^^^^

Keep jumping it and you'll end up turning a $15 can of freon into a $300 compressor that needs to be replaced. Just fill it up with freon with UV dye, find the leak, and fix it.

[Ryann]

As you add gas the system pressure will rise above the threshold for the low pressure switch and automatically energize the compressor clutch. The compressor does not need to be spinning before adding gas! If you were to energize the clutch with a jumper wire while the system is low on refrigerant the compressor would pump itself into a vacuum and suck in atmospheric air through the leaks, contaminating the system with moisture and non-condensables.

As previously suggested leaks should be located and repaired and the system properly pumped down before recharging in order to fix it long term.

[u3b3rg33k]

It's all been pretty well said, but just for kicks:

so everything was working fine --- but slowly ac started losing its cooling. I was too lazy till today it stopped blowing cold air. Now compressor wont turn on . everything else works.... so its got to be low on freon.

now please tell me how to jump the compressor. pics would help.I understand teh compressor has to be on before i can feed it freon.

91 325i..... no hacks or anything previously done. was working 100% but slowly ran out of cold then cool .. now ambient air only.

yup
yup
yup

NO!!!!!!!

[e30moneypit]

well i was able to add freon without the compressor kicking on..... however the compressor still wont kick on. Even if I feed it live 12+ it wont engage. I unplugged the single wire from harness and feed it 12+ and nothing clicks. ... buddy says clutch prob went out. But out of the blue????? I find it odd but whatever..... so can I replace the clutch without opening the compressor to atmosphere....

bently doesnt show how to repalce the clutch....

[Ryann]

You may be able to get the clutch off with the right puller, idk. I tried to on my father-in-law's e30 compressor but the inner bearing race stuck to the shaft on the compressor. So then I tried adding heat to the race in order to get it off and toasted the shaft seal.

[smooth]

If you find out you need some parts let me know because I don't use mine but haven't removed it because I don't know how to do so without ruining the parts. I don't know which parts can and can not be exposed to air, for example. So if you need a working compressor I have one but will need advice how to get it to you in working order.