I wanted to offer a couple tips I've learned about how to fix air conditioning in these vehicles if yours has stopped working. In my case, I was no longer getting any cold air and my 'snowflake' light would always blink when I tried to turn on the A/C. I figured the car was probably low on refrigerant (R-134a) so here is what I did.
(1) To add refrigerant, you must locate your low pressure port. The AC low pressure service port is directly behind the engine, about 5-6 inches back, in the center. Look for the two silver pipes coming out of the firewall. The larger silver pipe has the AC low pressure service port sticking out the top with a black dust cap. You can't really mess up the connections, as the low pressure port diameter is smaller than the high pressure port diameter, so the attachments are built to spec.
(2) Once you've located the port, you will need a hose with a pressure gauge to inject refrigerant from the can into the system. I highly recommend the ACPRO hose with gauge, as I first tried to inject the refrigerant with a tap and had no luck. I could not get the refrigerant out of the can and into the system using the tap.
(3) SUPER IMPORTANT STEP. Your AC system will not accept refrigerant if your vehicle has no refrigerant left because the AC compressor will not turn on. This is a safety feature - without any refrigerant, the car's computer tells the compressor to shut off and stay off because you could damage the compressor otherwise by running it for awhile with no refrigerant. This seemingly presents a problem, if you have no refrigerant and the compressor will not turn on, how can you add refrigerant if the compressor must turn on to accept more refrigerant into the system?
(4) HERE'S THE TRICK. You must manually engage the compressor. In normal circumstances, if you still have a little cold air, this means your compressor is turning on and you can add refrigerant by turning on the AC. BUT SAY YOU'RE GETTING NO COLD AIR AND THE COMPRESSOR IS NOT TURNING ON. Here's what you do. Open up your car's fuse box and locate the large AC Compressor fuse that has four pins inside. Next, get a paper clip. If you look at the four pins, you will see there are two pins labeled '30' and '87.' Take your paperclip and stick one end inside the '30' pin opening and one end inside the '87' pin opening. Make sure the paperclip is fit inside the pin openings well. If you listen closely, you should hear a click underneath you. THAT'S YOUR COMPRESSOR COMING ON! Congratulations my friend, you have now tricked the car's computer by bypassing the automatic shutoff and turning on your car's A/C compressor so that you can now add refrigerant into the system!
(5) While the compressor is turned on with the paperclip trick, connect your refrigerant hose to the A/C low pressure service port discussed above, squeeze the ACPRO trigger, and add refrigerant to your system. Once you've added a can (make sure the A/C pressure gauge stays within about 35-45 lbs of pressure - you don't want to add too much!), go inside your vehicle and you should feel the cool breeze. Next, turn off the car, remove paperclip, put the A/C Compressor fuse back in and put the dust cap back on the A/C low pressure port.
(6) You are finished. Now, when you turn on the A/C in your car, the snowflake light should no longer blink, you should get cold air, and your A/C compressor, with the added refrigerant inside, should automatically cycle on.
Hope this helps some folks. Cheers!
*** this procedure worked great for me, but as always, if you don't feel comfortable with the procedure, take your car to a certified mechanic ***