How easy is it to replace a/c refrigerant on 2003 grand prix

I flipped on my a/c today and the blower is blowing warm air. I can hear the compressor click on, but no cold air. I'm thinking the refrigerant needs to be re-charged. I believe it is R-134a. Am I correct? How hard is it to get to the valve to recharge it in a 2003 Grand Prix SE?

Thanks

It is R-134A. Recharging it is not hard but it would be a good idea to find out if you have a leak or not. I would get one of the cans of R134 that has the gauge so you can be certain that you need a charge. You will need to connect it at the low pressure port and run the car while you put the charge into the system. If you find you have a fully charged system then take it to a shop for diagnosis as you may have other issues.

Can you direct me to the low pressure port?

If you do not know what you are doing then I would not try to do anything. You can be injured by connecting the can of freon to the wrong port.

It's the only one the valve will fit- up by the firewall- with the blue cap on it....It is on the aluminum pipe that exits the evap at the firewall..

On my GP it has black caps on the service ports.

Thanks for the help. I found blow by blow instructions on interdynamics site, so I am going to get teh ez R-134a can and try it tonight. If that doesn't fix it, i will take it in.