AC blows warm different problem then the rest

I run a 2008 workstar with a cat engine. Not sure exactly which cat is under the hood as the company owns it and can't see the engine plate to tell which one it is. I have had them try all sorts of things to get the AC to work. All test come back good. Problem is AC works at high idle but not when working truck. At one point they changed the settings in the comp to get the fan clutch to kick on at 175F instead of the 220F that it normally does. This did help in keeping my AC blowing cool. Problem was fan was almost always on. Truck normally runs at 200F when working moderately. So I brought my concern about fan almost always being on so they switched it back to 220F kick on. Been reading a lot of forums and was talking with some other drivers. The one thing they though was condenser icing up. Just not sure in my mind cause as soon as I stop driving and put into high idle within 2-3 AC blowing cold. Engine fan is on a lot during high idle to cool coolant temp down to 170F. Does this really sound like icing up? Seen about the orifice being block but I have a puddle under truck where all the other trucks do. Just seen a post on a different forum about a control module maybe not telling the comp to turn engine fan on to help cool AC. Basically I guess my question is can the condenser deice within 2-3 mins at high idle? Just seem strange to me cause that cat throws so much heat through the cab that I can't see it icing up. Oh and I'm the only one running a cat the rest have those junk intl engines lol sorry for the long post just trying to put everything in here I can think of. Thanks in advanced.

 

Hmm you make a good point. I should see what it does at low idle. Just wondering how high rpms while driving wouldn't be the same. Yeah the more I read different post the more it doesn't make sense. I have had 5 different mechanics look at it and they all say the say thing. It's charged. They have runs vac test for a few hours nothing wrong. They all put it in high idle leave it outside come back about an hour later and say it blows cold air. Wasn't until they switched engine fan to lower temp that something just didn't seem to make sense to me. Also should have said going to get them to check air gap on compressor. The more I know the worse it is for our mechanics lol