The system is charged, the fan looks working, but the a/c works well only when the cars is moving. What is it?

We think it works well if the "rear ac" is on, but that's not normal anyway.

The system is charged, a autozone tester say overloaded but thegauge of a technician says is ok, then who knows. The fan is working and the car never goes overheat, then I guess that fan is working good.

Any clues?
Summer is close!

 

I had my system overcharged, until it made the engine run rough, (04 Saturn ION3) I found a local shop that was doing A/C Checks, and they were able to bring it back to normal. Then pointed out that there is no leaks, because it was over pressurized, so it was good. Hope that helps.
Tobie

 

At the end I pass the car with the guy with the A/C machine, that wich vaccum gas and air, the recharge it and test the pressure... Doesn't work... The compressor is not working.

 

Does anyone know about a video or instructions how to change the compressor. Is not located like the others volvo engines