Getting a service guy in my area is an act of congress. The story is all the same. They are busy. The first hot day of the season, everybody's AC does not work, so they are swamped with calls. So I have ended up fixing the thing myself. Not this time, maybe you can help me.
My unit is a long out of business Williamson five ton heat pump. The heat pump never worked, but I did not figure that out until just after the one year warranty. BTW, remember the AC guys being too busy to come out? I bought the unit and installed it myself, it is a five in one, Ok, stop laughing, I fell for the marketing hype. I really did think that a factory assembled unit would be worth scrapping a perfectly good five year old oil furnace. The AC part came with precharged components, including the lines, so I just connected it all together, and it has worked reasonable well since 1984.
The second season, the AC was dead. Turned out the high pressure limit switch was tripped. I pushed the button, and all was well. It tripped because the reversing valxe never worked, so when I tried to use the heat pump, it immediately tripped. Since I never really needed the heat pump, I lived with it.
In its lifetime, I have replaced the contactor, and a plenum control. No biggies.
On a few ocaisions in the past, I had the evaporator ice up. My bad, time to clean the filter. Funny how those things can slip your mind.
Not this time. To be sure, I took the filter out, checked all of the ducts, returns and vents, all unblocked. And the air flow seems to be normal.
The A coil starts to ice up from the bottom. After twenty something years, I thought perhaps it might just be dirty since all of tha air goes through it. I was able to remove an end panel and looked. Nice and clean. I shot some compressed air through it, no problem.
My research indicated that the most likely culprit is an undercharge. Why now? Is it normal for a twenty something year old unit to lose freon without an obvious leak? I have not seen any evidence of a leak, but I do not have a set of manifold gauages. I used to when I installed after market AC systems in cars decades ago. No AC technician talent needed for that, I am living proof.
Could the true reason for "why now" be that I am replacing this entire unit with another located in a new addition later this year, and only need it to operate for about half the summer? The new unit has dedicated ducts to the ceilings.
Anyway, the A coil ices up, starting at the bottom, about four inches pretty quickly, then gradually works its way up the coil, taking several hours to complete the journey.
I know it is not technology correct to just squirt in a little more freon like we can do in auto systems, but I wonder if this is possible and worth a try in the absense of having a competant repairman available. I am sure the government frowns on it. Hey, I am half handy for a reason. It would sure be nice to get this thing working for the weekend. In any event, I will try, try again to get an AC guy here Tuesday, but I am leaving Wednesday for a week, and don't want to leave the family behind sweltering. Can't help the trip, something has to pay the bills.
Thanks for your help.