FIXED as of 3/26/24! The culprit turned out to be sloppy welding. When the G805 port on the liquid line leaked at the base, I removed the liquid line and paid a local welder to "fix it". He reattached the port but also mistakenly filled the orifice with weld so no pressure was available at the G805 pressure sensor. He never checked his work, just reinstalled the G805 sensor w a new O-ring, and told me it was ready to go. My mistake was not removing the G805 and doublechecking his work.
Based on 8 months of working on this, the AC system functions as follows. The J301 manual module (located in the dash) controls the AC by reading the high side pressure at the G805 sensor. The G805 is a "transducer??" which converts pressure into a digital number. When the J301 reads a BAR (BAR = high pressure/14.7 corrected for altitude) of more than 9 (approx), the J301 sends a request (using the CAN network) to the asking the to turn on the condenser fan. Because my G805 was cut off from high side pressure by excess weld, BAR remained at 2.2 no matter how high/low the high side pressure was.
The one task I chose to outsource, welding the line, wasted months chasing phantoms. The blocked orifice was truly a needle in a haystack. When I finally removed the G805 from the orifice, I noticed the Schrader valve pin was bent. That led me to the problem.
, it's better charge to the AC on a VW using weight versus R134 gauges. I evacuated the system for 3-4 hours and waited 3 more hours for any leakage. Although I had R134 gauges attached and observed low & high side pressures, placing the R134 cannister on a gram scale and waiting until 500 grams went in, is the most efficient procedure. For the next hour after I completed the charge, my wife drove the car so I could observe Refrigerant Pressure, Compressor Load, Coolant Fan Activation, actual and specified, using on my laptop. System works great. Fan goes on and off depending upon the load.
Other items... amongst my many investigations I removed the compressor and tried to drain the PAG oil into a can so I could measure it. Nothing came out which suggests the oil escaped at the liquid line when the fitting leaked. I removed the condensor and flushed it. No oil came out. I blew out the open lines and but no oil came out. I added two oz of PAG thru the low side port on the open compressor. I rotated the compressor by hand after applying 12vdc to the compressor control solenoid so that the swash plate activated but only 1 ounce drained out. I replaced that 1 oz before reinstalling the compressor.
Comments and corrections are welcome especially how to get all of the oil out of the compressor.
