I had the same occurance. 1st time was vac leak by the battery. 2nd time was low freon charge, 3Rd time wad collapsed vac line from pcv to intake at the elbow on the back of intake. Once you lose ac, check to see if blowing out defrost vents. This is a vac issue. If lose ac then switch to heat and let it run. You may hear ice drop under the glove box. Floor may get wet too. Then need ac charge. Can just use a can from auto part store.