Air Conditioning problems - pressure good, compressor wont kick on

[jcharles00]

Maybe a little different than the way it sounds...

AC has always been an issue in this car. Long ago had a leak in the condenser, and I replaced it. worked for a while, then started having this deal where I'd have the mechanic fill it up, it'd work for a while, then the compressor would just stop coming on. Mechanic would put it on the machine and say "it's in the right pressure range.. *shrug*" after topping it off, it'd work again for a bit. No leaks. Mechanic did dye twice, I did dye myself twice. neither of us could find anything. I've been topping it off with suicide cans every now and then when I need it, and it's the same deal. I put the can's gauge on, and it's reading in the green zone, but the compressor wont kick on till I goose it a little bit.

I'm wondering if there's a pressure sensor that keeps the compressor from coming on if it thinks the system pressure is too low, and it's just out of spec. Anyone have an opinion on this being the case? Short of trying to change out such a sensor, I thing my next step will be trying a new compressor.. this one (2003) is pretty old.

[jayoldschool]

The relay is a common failure (from what I've read).

[vibrologist]

If it is not the relay you may try to have the whole system evacuated for a several hours and then refilled. Using the suicide cans may have introduced moisture in the systems. Pulling vacuum at very low end pressure can remove moisture.