Hello everybody, the only Nissan I ever owned was a 1975 280Z. I turned 70 yesterday and just wanted to share some old man wisdom. Bringing up the temperatures on the Geospring to figure superheat is kind of tricky. It is easier to look at the evaporator to "see" what's going on. If the lower tubes are becoming frosted and the higher tubes are dry, your unit is low on freon. If the tubes are sweating, but not all the way up, you are probably leaking some freon and the unit could use a charge. My Geospring seems to like about 40 psi on the low side after the compressor has been running for thirty minutes. At that point, all the tubes on both sides of the evaporator are sweating and the output air is very cold. Check the evaporator now and then to look for these tell tale signs.