How can you find out if a system has a proper refer charge by only using guages and a p/t chart? Ive always either weighed in a charge or used a glass charging cylinder.
super heat-subcool....and other measurements as well...
a thermometer is also very useful!!
you cant charge a unit with only gages
go through some on the earler post on chargeing mothods and read them
then you can do it right
Look to see if there is some data on the unit, a piece of paper that tells you all the information on the unit, if you have it. Then you can match up the pressures to that and be pretty dead accurate.
what's a matter don't you trust your air conditioning guy?