I have another thread called 2002 Power Stroke A/C which describes the issue I am having. I ran lots of tests and experiments and tried a blue orifice thinking I could get the low side pressure in the evaporator up enough to keep it from cycling off on low cutout. That didn't work.

question: what is the spec for the low cutout on an F250 2002 SD?

Observation: With either the blue orifice or the spec'd red orifice I notice that when the engine is rev'd up, the superheat goes way up for a spell, even though the suction pressure drops significantly. I can understand the superheat/suction line temp going up some when the rpm is increased from idle to 1500k but I saw temps of about 63 degrees on the low side line that lasted for about 15-20 seconds before they started coming back down again.

I attribute this to the compressor sucking the freon out of the evaporator at a rate much higher then the high side could feed it. Then as the system stabilizes at the higher rpm, the temp starts dropping again, ie, the high side feed into the evaporator catches up.

Has anyone else ever noticed this? I'm wondering if my problem may be that there is a restriction on the high side which is keeping the suction pressure so low. I'm going to measure various points on the condensor tubes to see if I can detect a noticeable and above average drop in temp at any point in the tube u-bends. Sure don't feel like trying to flush the condensor.

The other reason I wonder about this is that there was some crud on the filter screen of the original red orifice when I removed it and some of the crud was little metal chips or shiny flakes. It didn't bother me too much until I pulled the blue orifice out which was only in there for less then 3 hours compressor run time and it had some shiny flakes on it too.

Thoughts?