What should I check for weak air-conditioning

Hello all,
My friend has a 1996 (i think) chevy truck (sorry don't know exact name or model). Anyways she went to turn on her air-conditioning for the first time this season and found that it doesn't get very cold. The blower motor blows as hard as always but the temperture of the air isn't very cold (but it is colder than ambient air temp). Any ideas? Does it just need repressurization? -if so how do I find the the leak?
I'm a moderate garage tinkerer. I can read wiring diagrams, I have tools and to top it all off I have common sense. Can this be fixed by an unexpierienced garage monkey? Is there much room to break other stuff?
And if it does need a recharge will they sell me the stuff? (if not any advice on how to get it otherwise?)
THANKS FOR YOUR ADVICE You need special equipment to (a) find the leak and to (b) check the pressure. If A/C components must be replaced you must be able to (c)evacuate the system and (d) recover the refrigerant -- again requiring special equipment.

It's possible that this system can be improved by a simple recharge. If you want to take the chance that's all it needs, then basic recharge kits are available for DIYers.

www.aircondition.com

is a wonderful site for learning how to servise your a/c system. It's not really something for trial-by-error.

You can buy a pressure gauge from Meijer that hooks up to the low or high-side ports for about $16. I like to monitor the high-side pressure while I charge the refrigerant in to the low side.

But the motor vehicle a/c system is most correctly charged by weight instead of by pressure. If you can start with an "empty" system (which would technically require rather expensive equipment... namely a vaccum pump) and put in exactly what the sticker under the hood says is necessary for the system, then you'll be good to go with the amount to charge in to your system.

Finding the leak is done in a number of ways. You can check all exposed lines and components by using soapy water. The evaporator is a little more tough to diagnose. That being said, though; If you've checked everything but the evaporator and found no leaks, then you pretty much know it's the evaporator.

If you don't want to pay out the ying-yang to get it fixed (if it's the evaporator), and the leak isn't too bad, you can get by with recharging as needed.

Keep in mind it's best over the long-haul to have it done correctly. If you have to recharge periodically you don't know how much oil is in the system. If you let it get too low it's not good, if you put too much in it's not good. Best bet would be to fix the leak(s) like you intend and study up at

www.aircondition.com

to learn how to be safe and effective at maintaining an a/c system.

Good luck.