have a 2000 excursion with a a/c problem. checked freon level -fine,checked fuses in both boxes-fine,checked for juice at the a/c clutch with tester and no 12v. any ideas on this? thanks

check ac relay and low pressure switch

would the ac relay be the one in the power dist. box? where would the low pressure switch be located? what is the best way to test these? thanks