Originally Posted by deepstuff
I'm trying to charge my A/C but can't get the compressor to run. Its cold outside, 0 degress Celius. Could that be why the A/C won't run? Could the lack of freon chagre pressure cause it not to run? Help the refrigeration guy doing the charging is not cheap.
Is my compressor or clutch gone or could there be there another switch in the controls that is stopping the compressor from running?
The compressor may not engage if the system is too low on refrigerant. The low pressure cutout switch will prevent the compressor from running if the system is too low on refrigerant (this is done to protect the compressor from damage due to a lack of proper lubrication). The compressor must be running to suck refrigerant through the service hose into the system. So if it is not engaging when you turn the A/C on, you can jump out the low pressure switch connector, with a small wire or paper clip.
From the link below follow the low pressure line & you will see the low pressure switch, unplug it, & jump it out, the compressor clutch will engage, make sure you have the can of 134a ready to go when the A/C turns on, after the 1st can, you can remove the jumper wire & plug it back into the switch...
The A/C compressor should run in a cycle mode until proper pressures are reached. Pelican Technical Article: BMW Air Conditioning Maintenance and Upgrade