Yep:

 

Well it has been working better lately. But i've notcied that when i rev the engine up the low side pressure drops? I thought when the engine reved up the pressure was suppose to go up? Anyway at idle the pressure is around 35, but when you rev it up it drops to medium to low 20's. Which then kicks the compressor off. Is this normal for it to drop that much when the engine revs?

 

It's normal for low side to do that. It's more important to see what the high side is doing. Get rid of that single gauge and get a pro-style manifold with two gauges so you have a complete picture of what's happening.

The compressor will normally cycle off because the evaporator temperature reaches close to the freezing point. Revving the engine increases cooling capacity thus reduces evaporator temperature.

It will also turn off (via the pressure switch) when the high side exceeds 455 psi. That should never happen in normal operation. Of course you need to connect a gauge to the high side to tell if that is happening.

 

ok, what exactly is the high side for? Or what does it do i should say. Sorry i'm new to this a/c stuff. If you take it to an a/c shop do they put refrigerant in the high side as well as the low side? Or do they just put the correct amount in the low side?