| Usually, the engine should drop in RPMs when the compressor comes on, unless your car has some kind of regulator to put more gas to the engine when the A/C is on. If your system is empty, your compressor shouldn't come on at all, which would explain the jump in RPMs possibly, if you do have a regulator.
The refrigerant is added just like R-12. You hook up one hose to the tank, which would go to the middle fitting on a set of pressure gauges. Then hook up another house (blue) between the blue gauge and the low side of the system (near the accumulator). Open everything up and fill the system until you have about 34psi I believe. Do this with the car running and the A/C on. You'll see the compressor clutch engage and disengage a few times until there's enough pressure to keep it on.
This is after you pull a vaccuum on the system. You basically get a vaccuum pump, hook up a hose between the pump and the middle fitting on the gauges, and the blue hose again between the blue gauge and the low side of the system. Turn on the pump and you should be at about 30psi vaccuum. If it takes a while to reach 30psi, you have a leak somewhere in the system. Leave the pump on about a half hour to drain the system of any moisture, then close the blue gauge and shut off the pump. The system should hold the vaccuum. Let it sit for another half hour. If there's no change in the pressure, you have no (noticeable) leaks and you can charge the system.
That's all I can really think of now. Maybe someone else can add in a few things, since I've only done this once. |