There is some sort of pressure switch (?) on the high pressure side found under the receiver dryer a few inches but on the high pressure side (small tubing, steel). This is after the condensor and most monitoring of the high pressure side is normally done before the condensor (right out of the compressor high pressure side). Would it be okay to put a tee on the pressure switch mounting and mount the pressure switch on one leg and a R134a fitting on the other leg of the tee and still get accurate monitoring of the high pressure side? This would eliminate brazing a fitting on the pipe directly out of the compressor. It would seem to be okay since the pressure would seem to be the same anywhere on the high pressure side whether before or after the condensor but I need another sanity check.

I asked this embedded question below and got an answer from Mike Gambone (thanks Mike) who wrote "Generally, the drier is on the low pressure side. Basically anything between the compressor output (high side) and the expansion valve should be OK. I put mine on the steel (yes, steel) line that is between the condenser and compressor (after the flex hose at the compressor). You can have a shop braze a fitting on (need to look for hydraulic, AC line shop). Its under the car, but I can hook up the gauge without lifting the car. Volvo is still learning about AC, thanks to Volvo I learned AC. Good luck."