My AC will cool for a minute or two when the engine is cold, but after the truck has run for a little while it begins to blow hot air. The AC compressor does not cycle on.

I had the unit charged with coolant a month ago in Missouri where I live. I would be happy to take it back to them, but I am in Houston, TX for the rest of the summer.
I bought an AC Pro coolant kit. I can't get an accurate coolant reading if the compressor doesn't kick on, but it shows full charge with the compressor off.

I have tried resetting by removing the HVAC/ECAS 10A fuse. No luck.

I tried the procedure found at this link, but the module would not enter configuration mode.

HVAC Control Module Configuration Video by Dorman Products [size=13px]https://www.youtube.com/watch?v=O4LLJYNjTD0[/size]

That caused me to wonder if the Control Module is bad.

Any ideas?

gpbstevens

Could be the low pressure switch. At this age you might want to replace it just for good measure anyways.