I agree that you probably have a leak and jumpering the pressure switch plug with the ac turned on is a good test to see if the compressor clutch works. It's been my experience that leaks tend to occur in the "rubber" ac lines where the end fittings are crimped. Look for any wet oily looking areas near the crimped fittings. If one is leaking though they all should be replaced. If you can wait a couple of weeks you can try to find a local ac service company that may be able to save you some money by repairing your old hoses. I've had good luck sending mine to Century Auto AC in Phoenix,AZ. Even with shipping you'll probably save 50% over the cost of new ones. They just use your old fittings and reattach them to new lines.