My 2003 GMC Sierra has a problem with the AC, when I first start it up the AC works fine and blow cold on all speeds. A few miles down the road approximately 30 to 50. The AC is still cold but the the air is barely come out of any vent low or hi speed. I will then stop for 15 to 20 minute then start up again and it works fine. Then 30 to 50 miles down the road it happen all over again. Please help

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#13986 Closed 2003 GMC Sierra public

My 2003 GMC Sierra has a problem with the AC, when I first start it up the AC works fine and blow cold air on all speeds. But a few miles down the road approximately 30 to 50, the AC is still cold but the the air is barely coming out of any vent at low or hi speed. I will then stop for 15 to 20 minute then start up again and it works fine. Then 30 to 50 miles down the road it happen all over again. Please help

Sparky

Sounds like your evaporator core is icing over. The most likely causes are a faulty clutch cycling switch or a sticking relay. When the problem is present and the engine is still running disconnect the clutch cycling switch on the accumulator tank. If the compressor turns off and the icing melts away within a few minutes replace the switch. There is a valve core under the switch that seals when the switch is removed so you should not have to worry about servicing the refrigerant.

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