Split system topping-up

[Yvan]

I have 10 years old LG 12 a/c split system, and since last year it does not cool as it used to. It is used only during summer, not for heating.

I have r22 manifold, so van anyone explain how to top-up with r22? I do not have vacuum pump, and I can not evacuate the gas and put 780 grams of r22 (as it is written on the label).

Where I am it is hard to find good a/c tech, and few I asked answered that they only top-up by pressure, not as I described above.

I have r22 P/T chart, and it is also clearly marked on the manifold dial. But I guess that it is not the same if I top up at 25 Celsius or

35 Celsius (75F or 95F), or while outdoor unit is exposed to the sun or in the shade. How do you compensate for this differences?

I measured temp by inserting temp sensor an inch in the indoor unit, and it shows 7.5 Celsius (44.6F), while my other aircon shows 5.5C (41.0F).

[Steve]

charge it by superheat and subcooling.

[Stormin Mormon]

If he's in the USA, he'll need an EPA card to operate, legally. Of course, we don't know if the system has a restriction, or some other problem is causing the poor cooling. Who knows, might even be (cover your eyes, everyone) the condensor needs cleaning. (Safe to open your eyes again.)

[Stormin Mormon]

Steve's right, to check superheat and subcooling. You'd want to know that, to see if there are other problems with the sstem, that a quick top off might not reveal.

So, where are you? If you're in the US, I presume your have your EPA card?

[Yvan]

Nedavno Stormin Mormon napisa:

I googled for a while, and it seems that I need some special thermometer for charge by superheat and subcooling. I am in Serbia, and I think that it will be hard to find it here.

Any links to a/c charge by superheat and subcooling, that a novice can understand?

BTW, I only noticed that a/c does not cool as it used to, it seems that it gradually got like this. Most logical (to me) is that it needs toping-up. Would some restriction give similar effect?