Piston coating is my guess, personally I'd put in new orifice,, pull good vacuum and charge up to sticker weight refrigerant. Maybe get few more years out of that compressor? Others might have a different opinion, it's just a money question, how long will you keep this car will inform your decision...

Paul, I've read again the whole thread, I think it's undercharged. I know you've said the correct charge by weight is being installed, I think maybe it's not being done correctly. If you are SURE the correct charge amount is being added, I think the orifice tube screen is clogged with debris. In ei...

Paul, I've read again the whole thread, I think it's undercharged. I know you've said the correct charge by weight is being installed, I think maybe it's not being done correctly. If you are SURE the correct charge amount is being added, I think the orifice tube screen is clogged with debris. In ei...

" I read that it was a way of checking correct charge volume" Not really. If you have an accumulator and thus an orifice tube, the flow is like this, as Detroit diagrammed: comp-->condenser-->OT-->evap-->accum--> back to comp OT and TXV are very different expansion devices My apologies, y...

Paul, diagrams of this car that I can find are pretty useless, but it appears to me to be an orifice tube system. I think what you see as a receiver is in fact an accumulator? confirm? are the pipes going in and out of this "can" roughly 19mm diameter ==>Accumulator, or are they 10mm or l...

Maybe one of the shops shoved an orifice tube in the liquid line? There is an old style tube-o threaded connection a few inches upstream of where the frost happens I did wonder myself if there could be an orifice tube in at this location (that might be partially blocked). I don't seem to be able to...

If you have ice on the high-pressure line six inches before the TXV, I'd say that there's some kind of restriction in the line just upstream of where the ice is beginning to form, causing evaporation to take place in the line itself before the refrigerant passes through the TXV into the evaporator....

At ambients that low we are gonna have to let the heavy hitters here wrangle with this. Did this car ever cool properly at 66F? Have to wonder if the other car has some type of special equipment on board to make it work..... Yes, it used to be ice cold, even at 66F. I'm not making this up, I promise.

Static pressure at 22 C was just over 70 psi. But the running pressure was the same, 25-30 psi on the low side and 100 psi on the high side. Holding higher revs on the engine makes no difference. As already called out, your testing temp is too low to be of any value. 22°C is 71°F. In a system with ...

I've just been out and check everything again, best I can. Static pressure is approx 68 psi, at an ambient temperature of 19C (66F) (which is the same as my other car where the air con works fine). With engine running at 2000 rpm, pump is engaged, fan is running. Low side pressure reads 27-32 psi, H...