A/C Compressor Not Working on 2000 Cadillac Seville STS

Finally had a warm day this weekend and wanted to use the air conditioning but found that it was blowing only hot air. I thought I might be low on refrigerant so I attempted to load a can of freon. However, the A/C Compressor will not engage. I have checked all the fuses and relays...everything appears to be fine there. I attempted to jump the pressure switch with no success and also disconnected the battery cable thinking that the computer would reset. Other than a bad compressor is there anything else that would prevent the A/C compresor from engaging? Any suggestions would be appreciated. Thanks.

Asked by for the 2000 Cadillac Seville STS
last year i had my a/c line replace because i had a leak in the line. This year my compressor will not engage what can i do to fix this problem myself or what do you think the problem is. 2004 cadillac srx awd 3.0
1 more answer
This problem was fixed by a local Radiator & A/C specialist. Turned out to be caused by a bad relay and two bad sensor switches. Don't have any specific part numbers or locations of these items. Total cost parts & labor $295.