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Why does ac quit blowing cold air after two hours Park for 30-45 min and starts to blow cold air?



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Next time it stops blowing cold air, leave the engine running, AC on, and open the hood. Check the AC lines under the hood. If you see a lot of frost buildup on the AC lines, there's a good chance you also have frost buildup on the evaporator inside the air-handler. It's called "icing-up", and it's generally caused by someone over-charging the refrigerant (over pressure). When you build up too much ice, the air can't blow past. You could need a charge & too much air in the system Have it done right just dont through in a can.Vacuum down the system check for leaks.add what your car/truck call for don't mix them up 134a or 12 one or the other. The other problem could be your compressor clutches or bearings are ready to go listen for metal to metal noise.But you are most likely just low on 134 or 12 the compressor will cut off if too much is in there too. so if you just put a can in let some out and check it with a gauge. Good luck.