2004 Jeep Liberty air conditioning question. Compressor replaced last fall and ran cold. Compressor clutch not engaging now. Have used jump wire on low pressure switch and still didn't kick in. Applied separate 12 volt source to pigtail that sits on top of compressor and clutch engages that way. Engine compartment AC fuse is ok, Driver compartment AC fuse is ok. Why isn't the system delivering power to compressor clutch on its own?