Wire running from compressor to on /off switch is lose on my 2003 325i wihich in turn vibrates and dose not let clutch ingage

You say that you can hear the compressor turning but that it is not engauging? Is it that you hear the blower motor running and not the compressor? Hook up a set of A/C gauges and see what the pressures are while the car is NOT running. If the pressure is less than 40psi then the system does not have enough pressure to close the low pressure switch and the compressor will not enguage. Recharge the system. Start the car, if the compressor enguages for a short period of time and then stops see what the pressures are reading. If the high side is over 450psi then there is a problem with the system and the compressor shuts down.
If the hub is slipping on the clutch assembly then it is either worn or the magnet is weak or it is not getting enough current to keep the clutch enguaged.

I'd check the A/C Fuse & Relay- Check your owners manual as it may not have a fuse, but it'll tell you. It could be the switch inside of the car not working properly when you turn the A/C on, but if not It's likely the A/C clutch itself, you'll need a new one or a new conpressor assembly if so.

Thanks & have a great day!

the AC compressor has a "shutdown switch" when not enough refrigerant is in the system run a wire from the

run a wire from the + battery cable to the compressor pulley switch with the engine running, ac on if the compressor clucth engages (turns) you have low refrigerant charge





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low freon level will prevent clutch from engaging. or disconnected high or low pressure switch

sounds like you are low on freon, that would be the fist place to go. the system has a low pressure switch that when the freon gets low it will not allow the compressor clutch to engage.

you don't need to jump the wires. even if the compressor clutch is not turning add the refrigerant to the low side port, it will go in through its own pressure when a safe level for the compressor to run has been reached the clutch will engage. at first the clutch will spin a second or two and stop and then begin again, from there continue adding refrigerant the clutch should spin continuously. if the clutch fails to ever engage the compressor is bad or there is a wiring problem.

Check for voltage at the AC clutch with AC on and engine running. If no voltage there, check voltage at AC clutch cycling switch.

Before you start your engine look at the A/C clutch. If you want, put a mark on it with chalk or paint.
Start your car and turn on the A/C, then look under the hood and see if the A/C clutch is turning. It may cycle and try to work. If it does not there is a switch close to the black cylinder where the A/C lines run.

This is the low pressure side of the system. If you remove the connection and put a "U" shaped wire into the harness it will arc and engage the compressor while the engine runs. Do not plug this in with the engine off. If the compressor clutch works then your problem is low pressure or a bad low pressure swtch. If the compressor clutch does not work it is very likely the bad part or you blew a fuse.

If the compressor turns and sounds like a stone crusher your compressor is bad. Now if you have determined the compressor is good, the clutch is good,the fuse is good, you have to diagnose the low pressure.

You will need a gauge. Some cans come with them but they are not always reusable. If you add 1 can of Freon and use the "U" shaped wire where I told you, it will draw in enough to start the refill without the "U" shaped wire. You still need to measure the pressure so you do not overfill the unit. A completely empty system will take about 3 cans.

You can lose the Freon through a leak, there are leakstop chemicals for A/Cs. You may get assistance from Autozone or Oreillys on this matter. Freon usually lasts for years. I have replaced many low pressure switches and had immediate success where it was the ONLY problem.

You need to have it leak tested and recharged. There's a low pressure switch that won't alow the compressor clutch to engage when there's a leak. If the compressor clutch was engaged without refrigerant and oil circulating it would seize. Don't be surprised if you need a new condenser. Don't use those leak sealer recharge kits as they can do more harm than good, and some AC shops won't touch a car after someone uses leak sealer. They claim there's a different mix of gases in the refrigerant (usually propane) and they can't recycle it, and they don't like customers complaining when the AC doesn't work when it was the leak sealer clogging things up.

sound like your clutch disc ran out you need to change you clutch.