You most likely have lost pressure in your AC system. Probably the low pressure switch is sensing that there isn't enough freon in the system s it won't turn the ac clutch on.
It could be that the switch is bad too.
These are the most likely causes.
May, 6, 2012 AT 9:50 PM
You could try jumping the low pressure switch on the accumulator to test the electrical part of the circuit. But don't run it to long if its low on pressure its low on oil to. If it runs when jumped have the refrigerantlevel checked