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A/c work on and off at high rpm and the highway

I drive a 07 Mack granite. The mechanic replaced the clutch fan, compressor,drier, and the inside/cab control panel. When I shift at high rpm or driving in the highway (higher rpm) , the a/c work on and off. Sometimes the compressor stop working for a few minutes. But after a few minutes it kick back on, but doesn't feel as cool as suppose too. It's only happens on highway (65 mph/ speed governor) and if you shift at higher rpm. Work just fine around town ( if I shift on lower rpm)and when it's stop. Also the fan doesn't blow as hard like other truck , even on max speed

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Is it cold when you first turn it on and as your using it then gradually isn't as cold anymore? and the blow coming out air ducts is about half as much as normal?

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,,, sounds like more trouble than this, but it might not be charged to the proper level. Either too high, or too low, the fan speed is a separate issue,

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I am leaning towards to much freon or thermostat and its running to point it ices up the evaporate which would cut on blow out of air ducts and temp of the air. Air out of air ducts should be somewhere between 36 to 42 degrees with AC on high

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Just found out that the belt for the compressor was loose, a tiny bit low of freon. And the air flow issue I have , was a plastic bag stuck on the cabin air filter. Tighten the belt, put less than half an ounce freon, a/c blow cold now.

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That would do it

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When this happens try to get to the evaporator core and see if its freezing up. try turning the thermostat off and leave the fan blowing, see if you get a lot of water coming from your drain tube. If the core freezes it also blocks the air flow through the core.

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