Intermittent compressor

by brian
(montreal , Canada)

Recently my York central air conditioner unit 2.5 ton was working tirelessly on an extremely hot and humid day.

I noticed the air coming from the register wasn't as cold as it usually is. I went outside to the outdoor unit and although the fan was turning the particular sound the compressor makes was absent.

I came inside and called a service man who said I needed a capacitor booster. He installed this and immediately it seemed to solve the problem. Then he again pushed a switch at the outdoor unit and the compressor failed to start. He announced that the compressor needed changing.

I asked him to leave the booster on and I would try the central ac unit after I'd shut it down for a few hours. After a few hours the ac unit fired up and worked overnight.

It has happened twice and starts up after a few hours idle. I do think the ac unit is undersized, and has to work a long time before the temp. comes down in the house. The two days that this occurred temp was 35c and 33c with very high humidity. Any ideas? Machine is about 10yrs old