In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
have a 20 yr old residential AC system; over past few yrs (and maybe longer) the robustness of the cooling has diminished.
found out it was low on freon and 3 lbs were added (total capaciity is 9 lbs)
freon has never been added to system over 20 yrs till now
what are thoughts on leak (is loss of 3 lbs freon after 20 yrs reasonable?); guess this may mean that leak is minor/tiny
curious if adding 3 lbs may worsen leak via added pressure to system (head pressure was on the low side but not bad)