Car is a 2003 Grand marquis. I recently fixed the climate control module inside the car. I have been living with the vents switching from defrost to the floor for over a year. Very easy to do yourself if you are wandering. Now that it blows out of the vents all the time now, I noticed the compressor kicks on and off while driving with a long off interval in between, resulting in not very cold A/C. I threw my gauges on it, pressures was a little low, so I topped it off and went on. Next day, it was still doing it. Put the gauges back on, pressures was good. I throttled the car up to a little, about cruising speed rpm, and it kicked off. Watching the gauges, I done it again. Low side went from 45psi to 25psi (low pressure kickout)in about 5 seconds. High side was in range (best i could tell with the flutter). I assumed the orifice tube was stopped up, so I vac'd it out, and pulled the orifice tube out. Had a few little metal flakes on it. No blockage there. I put a new one in it anyway because I already had it. I put it back together, vac'd again and refilled with 38oz by the sticker, thinking maybe I still didn't have enough freon the first time. Well my symptoms still haven't changed. I did see something Ive never seen before and thats high pressure flutter. With throttle, you can't even see the needle its moving so fast. Im thinking the compressor is the updated piston pump due to the flutter. Im thinking maybe the previous owner shot it full of stop leak additive and possibly stopped up the evap? Or shot liquid in the low side and cracked something in the compressor. I hate to throw a compressor on it, without confirming its bad. But the flutter on the high side has me leaning that way. Speaking of compressors, If it comes to it, scroll or piston style? Scroll was factory, piston was an updated version. Sorry for the long post.