I'm usually the A/C guru around here but this has me stumped, I've never experienced this on anything before. The a/c is perfectly cold, most of the time, I've noticed lately my compressor cycles a lot while cruising down the highway and and creating enough load to feel it in the vehicle movement. I hooked up my gauges and the low side is normal but the high side is hitting 450psi at 2800rpm. Normally I would think clogged orifice tube but when I've experienced those on the past the low side was low. This is acting more like a over charge, but it was last charged 2 years ago when I replaced the compressor and it was fine the last 2 summers and nothing has been added since. Condenser fan roars at cold start up and after sitting running in the heat for a while so I'm pretty sure the fan clutch is good. As I said before it's cold "most of the time" there are 1 minute periods where it starts to get warm I'm guessing once the high cut out switch has been triggered and it takes a min for the pressure to go down enough to come back on... I looked it up, high cut off is at 430psi and cut on is at 285psi. Just in case anyone coming across this thread would like to know, the low cut off is 25psi and the low cut on is 44psi. According to this http://www.chiltonlibrary.com/content/images/Ford/S3N/S3NC0007.pdf that high of PSI is normal if it's 120 degrees out. It was about 100 degrees when I tested.