[JustSayGo]

When did the A/C last work? You could jump accross the low pressure switch or plug and read the gauge on the service can. If it shows a vacuum or very low PSI, the system is more than a little low on freon. My concern would be that there is a leak and that whatever I pay for freon will be lost and it still won't cool any air. If all the freon has leaked out because of a leak there is probably air and some moisture in the system. Systems filled with air that has warmed and increased pressure can show pressure high enough for the switch to connect for a second. Don't add oil. A slow leak won't carry oil with the freon as it escapes. No sign of oil leaking from any part of the A/C? R134a makes it very difficult to find a leak for that reason. Ultra-violet dye and a powerfull UV light are the tools that make finding leaks easier. The most common place for any A/C system to leak is at the compressor seal because it is a moving part. An overcharged system or radiator fans not working will increase high side pressure and could shred the A/C belt or the belt could just have worn out.