Recently salvaged a 1993 jeep cherokee a/c compressor to go into my 91 cherokee. The new compressor is installed but the clutch won't engage and the refrigerant won't leave the can. I evacuated the system but didn't vaccum it. Is this the reason the can won't empty? Should I just send it to a shop, get them to check and make sure it works, then vaccum and charge it? Advice and comments please.

 

You have to put the system into deep vacuum and then charge with the can upside down. It won't start until there is some pressure in the system.