How do I recharge my central A/C?

Factual Questions
1

I have recharged car a/c’s many times, but it appears that my home central a/c needs one. It is only marginally working.

I assume that some panel gets removed from the outside, where the compressor is and there are standard valves (high and low side) where I can hook up gages.

Also the a/c was installed 96 - 99 (I don’t know exactly when, since I didn’t own the house at the time), what is the most likely freon and what are the other possibilities. If it is 12 or 22 can I use the more common 134a as a direct replacement?

2

After some looking it appear not to have valves but crimped soldered joints, what do I do with these?

3

Not to be a wise guy, but you need to do a bit of research before working on your home A/C. It seems pretty evident you don’t have a mastery of the science, as I’m almost 100% positive that the freon is R-22. (If you overcharge, you could blow out your system, or greatly accelerate its demise.)

R12 is for auto usage, Old Car Division.

That said, it isn’t rocket science to add freon to a home system. Of course, I take it you have experience purging a freon system, and have the necessary equipment to capture the freon lest it escape into the atmosphere.

Do some Googling. You’ll get plenty of how-to’s.

4

Service valves for home A/C are installed onto the piping when needed for repairs. They clamp around and pierce the tubing.

Do not use anything other than the type of refrigerant originally installed.

I’m sure there’s lots more to know than I can tell you, to avoid damaging the unit. If I were you, I’d do lots of research before digging in.

5

I would not recommend attempting to service your home AC as it’s a whole lot different than “jam a can of freon on the refill valve” like it used to be on old cars.

Last time I needed a home unit serviced, the equipment involved three connections and two gauges. Add to this the knowledge to properly use it, which is apparently not a “given” even when dealing with professionals. The technician quickly determined that the problem with my unit was another tech from the same company had overcharged the thing. He opened one of the valves on the gauge unit and blew quite a bit of Freon out (this was before the days of reclaiming the stuff) Just like that, the noise went from a “GRRRRR” to a “Whirrrr” and the unit’s electrical consumption plummeted (he had an ammeter on it) and the thing stopped short-cycling. How the compressor seals didn’t blow out was a mystery.

Why did the original tech overcharge? Read the wrong gauge? Bad gauge? Bad tech? Who knows. At any rate, it’s not a do-it-yourself project.

6

Isn’t it illegal for an unlicensed person to do this?