I just recently replaced a seized AC compressor on my 1995 E300. New compressor, new o-rings throughout, new expansion valve, very thorough flush of the condenser and evaporator as well as all lines. Flushed everything that could be flushed at least 3 times. A new receiver/drier was installed.

Oil and refrigerant was added to an evacuated system. I had pulled a vacuum on the system for an hour prior. After 2 cans of r-134a (680 grams) were added to the system I was getting 32*-42* temps at the center vent. I added just shy of a half can more of refrigerant. The center vent temps were still the same.

Here's the problem. With the gauges connected I am getting a low side reading of 25-30 psi and a high side reading of 165-235 psi (at 235 psi the auxiliary fan comes on) at 65* ambient temperature. The compressor cycles on and off, even with the system set to maximum cooling (recirculation mode). One would think that this would be because of the cooler ambient temperature but the next day the temperature was in the mid 80's with the same behavior.

I added the rest of the 3rd can of refrigerant to see if I may be undercharged and thus the cycling, but still the same behavior. The system is producing VERY cold air but the pressures don't seem right. The cycling of the compressor is not normal for this system from what I've come to understand. The engine temp runs a little warmer at times but it corresponds to the high side pressure. I can feel the compressor cycle while driving. Again, the vent temperature is VERY cold. A laser thermometer shows cool temps going into the evaporator plumbing and warm temps coming out on the high side. Same with the condenser. I haven't removed the auxiliary fans to test the temperature across it. Long story short, am I on the right train of thinking that there may be a blockage somewhere? Plenty of condensation on the low side hoses and drainage from the evaporator box. Help me out here guys. I don't want to burn up this new compressor.