Its 50 years old this year! Only half the evaporator is getting cool/cold Top half is room temp Ive never put in refrigerant in the 28 years Ive lived here. Its R22, and I have some It has no piston, no txv, just a fixed tube/capillary system Soooo... is it just low after all these years? My house is about 82 degrees, out of the vents is about 72 degrees. But, how do you know how much to put in? Ive heard the old "beer can cold" analogy, which tells me nada Dont want to overfill it. Ive done auto ac's since the 1970s, have gauges for R22, just not sure what to do here, cant afford to replace it, and love its simplicity to be honest. I imagine if its a leak its a sloooow small one. Could be a schrader valve, hose, connection etc, or maybe something more serious, but want to try adding for now and see the results. No one can first believe this system is 50 years old, and most start talking about pistons and txv valves, which dont exist, which they also dont understand or believe. All the techs Ive talked to have never seen much less worked on a system this old So how to add and not overfill? I should add Im in Florida, its been in the upper 90s with heat index in the 106 degree feel like, with 80% humidity. So Im sure its struggling, Ive lived around here since 1977 and this is the hottest and most humid Ive ever experienced. Amazingly, typically my ac in the summer spikes my bill into the mid 200s, now its hit mid 300s for the first time. 1600sf house, 3 ton unit On another need, what is the absolute safest cleaner for the evaporator? It needs a cleaning (not that bad, just want to do it) and Ive read some cleaners are caustic. This evap is old so I want something that cleans but is completely safe for it Thanks