What is procedure for adding freon to central unit?

Answer 1

Maybe! Hook up your freon tank to your guages and to the AC unit. Blow out the high and low side hoses of air with freon as you hook them up to the central unit. You do not want any air in there. Attach an accurate thermometer to the large return line at the AC unit. Turn on the AC unit. Add freon slowly to the suction line only. The high and low suction pressure will both rise. Soon the return pipe (large one) may be dripping water and very cold. I said slowly - this means it takes a while for that freon you added to mix up in there. Don't be in hurry or you will be back later. Watch the sunction line pressure gauge and the thermometer differences. Add enough Freon to get the difference of the attached thermometer reading (high) within ten degrees of the Suction line gauge temperature scale - (lower)reading of the gauge. - You are doing good then and will have a more efficient cooling system. I have been told you can try for a 5 degree difference. That is up to you. Some systems won't even go there. While we are on this subject - FIRST - Clean the evap coil in the house and the condenser coil outside. You may have to cut a hole in the furnace to access the evap cooling coil. Do it. change the filters too. woody