I have been in automotive cooling repair for quite a while, but this house stuff seems a little different. I have a 3.5 ton unit at home that will not cool. I know that hvac units run higher pressures than automotive, but I keep getting different answers about what the pressures should be. My high side pressure seems low (225psi) and the low side is around 70psi. The high side line is nice and warm, while the low side is cool, not cold, or sweating. Does a system like this carry a txv or some kind of restricting orfice? I know it needs something to drop the pressure, but I have no idea where to look. I plan on getting a package system next spring and I would really like to make this system last a little while longer. Any help or advice would be appreciated.