A/C blowing warm when temp of motor goes up?
 

When I am pulling my trailer and temp gets to around 210 my a/c stops blowing cold? But soon as I ditch the trailer it starts blowing cold again. Coming home from work yesterday. Started truck and A/C was not blowing cold.... drove 5 miles shut truck off waited 10 minutes ( while I was in the store) started truck and A/C starts blowing cold again. I have had a service done on a/c a week ago( and it was low on Freon), last year installed new compressor, air dryer. But did not replace the a/c expansion cause I could not find it. Could this be the problem?

Take it back to whoever serviced it! First thing they are supposed to do is find leaks! Repair them then fill! Half ass job gets same results! Most likely your suction discharge hose assy has a leak!

They did a vacuum test on the system and everything checked out fine. I also was standing right there when he did the test...

Hmm well with any system air flow thru the condenser is critical But it sounds like you have an electrical issue. Check your pressure sensor and wiring.
When you say "a/c expansion" Do you mean the inline Thermal Expansion Valve?
Read this may help! : Your Car's Air Conditioning Components

Yes its the screen in the liquid line. But this morning I heard a squeak noise and it got loader and started smelling a belt burning and seeing sparks. A/C clutch must be hanging up and was not kicking on when I wanted too. I think?

Nope the compressor is seizing! Sparks?? Something else going on clutch wasted already? But I bet the compressor is toast!