Buick Repair Questions? Ask a Mechanic for Answers ASAP
The lighter fuse will say "lighter",if you are unsure test all the fuses with a 12 volt test lamp.The lamp should show voltage on both sides of the fuse if it is good.
Your ac problem is most likely a vacuum leak.Check under the hood for vacuum supply going to the passenger side of the vehicle.
The INTERIOR fuse block is the fuse block that will have your lighter fuse.It is under the dash or on the ends of the dash carrier.
Check for voltage at the mode door actuator,while moving the ac controls.It should be on the drivers side,under the dash.