A/C blows cold at idle when i start going it stop blowing high and cold. blows low and
warm.when i slow down or stop it blows cold and high again
sounds like the compressor clutch is slipping at higher engine speed and catches up at lower rpm. Probably need to replace compressor clutch
YOu may have a vacuum canister on you vehicle to maintain vacuum when the vehicle is running at a higher speed. Check for leaks.
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