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Discussion Starter · #1 ·
My AC has not blown consistently cold at highway speeds for about 2 years now but today on my way back from Junction, TX going back home to Kingsville, the AC started getting worse. The AC only blows cold when the truck is accelerating or going up a hill but when slowing down or going downhill, it will start to blow hot, almost like the heater is on. With the cruise control set, the AC will go back and forth between hot and cold on level ground. It probably didn't help the AC any that it got up to 100 degrees ambient temperature today on my way home. So my question is what does everybody think could be wrong with my AC? Just needs freon? Maybe a problem with the compressor or condensor? Any help will be greatly appreciated and thank you in advance.
 

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Discussion Starter · #3 ·
I don't think this is the issue though. The AC runs fine in town and under acceleration bit at highway speeds is where is is intermittent, especially with cruise control set.
 

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Check it anyway. Sometimes the variance in alternator output is enough to reengage the clutch. It could be an undercharge as well. Increased air flow across the condenser might lower the pressures enough that it's short cycling. One way to tell would be to wire an LED light in the cab to the a/c clutch harness so you would know if it's getting power in the periods it isn't cooling.


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Discussion Starter · #5 ·
Thanks for the info, I'll give it a try ?
 
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