If this is similar to the 92 the the low side valve is under the air filter box. Remove the two bolts holding that. It is r134 freon. Add enough so the dryer under the filter box begins sweating. If it leaks out again in less than 3 months you might ought to find the leaking component - tho a can of r134 every three months is tolerable. There is a leak stopper available for small leaks.
Update: Just performed this on my 1998 Chevy Lumina. The valve is still under and behind the air filter box on the driver's side of the vehicle. You can see it without removing the box, but to attach the r134 can, you will almost definitely have to remove the box to have any room to work. There are two valves down there. The low pressure one is the larger diameter metal pipe that is underneath the smaller pipe.
it should be on the drivers side near the battery. somewhere on that side of you car.
on the bottom left hand side of the car remove the air filter housing and you can see it clearly.
on the low pressure side
The high pressure fitting is located either in the high pressure vapor line or muffler, while the low pressure fitting is located on the accumulator.......
Low pressure side of compressor (larger hose)
On my Chevy lumina it is located right by the gas take on the right side of the car.
The low pressure switch is mounted near the ac compressor. It is a two wire switch mounted in the low side line.
Yes, if you recharge it on the high side, you could blow up the can using to recharge it. So it is very important to use the low side.
It is near the back of the air filter box - that is just on the firewall side of the box. The fitting on the larger tube is the low pressure side which is what you want to use. You will see two fittings there the low pressure fitting is the one on the bottom with the high pressure fitting above it. This means the one you want to get at is harder to access - figures right? If you can't attach your recharge hose easily you may want to loosen or remove the air filter box.
on the side of the radiator
Not sure what your asking yes you charge from the low pressure port it is the smaller one your hose should not fit on the high pressure side