I'm ASE certified (Which doesn't really mean anything) and have been working on A/C systems for years without too many problems. Here's a good one for you guys though. I installed a new compressor, drier, evaporator, condensor, orifice tube, hoses, heater core, blower motor and controls in my 97. I've been driving for the last 3 years without a problem but decided to change things out because the blower wasn't blowing enough air across the evap since it was plugged. I charged the A/C system and it blows great and cools to 42 degrees which is great! My dilema is that when I first start the engine I can watch my discharge pressure hit 400 plus psi for a second, drop and come back up to 400 plus, drop and then level out at 225 psi within a matter of seconds but I get a P1539 high voltage code like I should. LOL The suction pressure stays close to 35 psi which I'm ok with and now that the pressures level out I'm doing good with cooling. Both electric fans are on and temperature drops. I take off down the road freezing my nut's off like I should and all of the sudden I get a P1546 Low voltage code. I run the gauges under the hood and prop them up where I can see what's going on and I see the dreaded 150 psi which drops the voltage to the pcm to 1 or less coding the P1546. Everything is new, I changed the orifice out again just to make sure there wasn't a little trash or debris on it and blew through the system again and everything looks good. I recharge, start the truck and have the same problem only at startup and only when driving. I know a little more freon will take care of the pressure issue on the road but the pressure is going to hit the pop off valve on the back of the compressor when I first start the vehicle. I've seen similar issues like this where it's been the compressor so I went ahead and got another new one under warranty. Oh, I have 8 ounces of oil in the system so I can't see that being a problem either. This sucks because it's my truck!! LOL I'm ok as long as I have a computer/scanner with me to reset the A/C code so the clutch will engage. Anyone seen or had an issue like this? Nothing has changed except for everything being new.