Vintage Air definitely uses a Thermostatic Expansion Valve.
My Vintage air has a A/C temp switch, it adjusts the compressor cut in and out pressures, so if it freezes up, I adjusts it up just a smidge. Its not as cold but it keeps from freezing up in high humidity. Also mine runs really low side pressure, like 5 - 10 psi when its on max cool and the cab is cold. I don't remember what the high side was. They don't hold much freon, something like 1. 4 lbs, but don't hold me to that number.
I am currently battling with my Vintage Air. I believe that mine is icing up and cutting off. The compressor makes a lot of racket and it feels like i am dragging a 10,000 pound trailer with flat tires when the A/C compressor is engages.
My low side is 19 psi, while the high side is as high as 275 on a 90 degree humid day.
I thought that it had been over filled with R-134A, but having some of it slowly removed (by a professional of course) it began to cut off from the low pressure switch.
I sure wish that I would have read your post about turning the temperature knob off of all the way to A/C position before I let out that R134A.
Before I messed with it, trying to make it stop cycling and dragging on the engine, I coulda hung meat in the cab. 42 degrees at the vent on a 90+ degree, humid day.
