I'm having troubles with my A/C compressor. At idle the clutch engages like it should but when I'm driving or it gets over a certain RPM (IDK what because I don't have a tach) it engages and disengages. I'm posting a link for the video I took. It starts with the engine idling then I gave it some gas.

 

Probably low on freon, low rpm there is enough charge to keep compressor on, but at higher rpm, there is not enough charge to keep the pressure switch engaged.

 

the system holds 2lb 12oz.. there's 2lb 8oz in there.. since there's that much in there do you think my pressure switch went kaput?

 

I think you're 4oz light.

 

would the 4oz make that much of a difference or should I go ahead and buy a new switch?

 

Well, try the 4oz or try the switch and 2lbs 12oz. You have to drain the system to install the switch.

 

Perhaps slap a guage on the low-pressure side to see where it activates - IIRC, should be about 28psi for R12, 22psi for R134.

Yeah, 4oz is light - technically. Don't know that you would notice otherwise. Some other thoughts -
* There is some kind of flow restriction with the freon - such as a plugged orifice or an orifice that is too small (something to look out for if the R12 -> R134 conversion has been done).
* Not moving enough air across the evaporator or the condenser to transfer sufficient heat. Might try boosting the fan speed up a notch or two and ensuring the condenser has clear flow.
* Fan clutch working OK?

 

wow that sucks.. i wish i knew about the switch before i put in the new line.. that means i blew almost $60 in freon.. where is the pressure switch located?