The compreesor is obviously putting out air because it would run continuously if it weren't. Two things to check are:
There is a black plastic looking hose near the master cylinder that we see come apart lot. It has a fitting connecting two hoses and it tends to seperate. If this looks ok and you see no signs of bubbling when testing with soap, then inspect the rear bags. They wear over time and start seeping out air. You can see little cracks in the bags and this is a good indication that they could be leaking. Bags are very expensive so make sure you have the proper diagnosis.
As for the Ford dealer ripping you off. I work for Ford and we often experience customers that don't understand or know how to operate their vehicles. Alot of times we are accused of charging too much. The facts are that when you bring your vehicle in for service, unless under factory waranty, you sign a paper accepting the charges for diagnostics. If the technician tests the system of concern and finds that it is operating properly, you will still be charged the diagnostic fee that you accepted. If the concern is not present at the time of diagnostics then the problem may not be identified at that time. The dealers that I have worked for stand behind all repairs made in their shop. If you have an issue with the services performed then you should speak with the service manager and explain your situation. However, don't expect to get everything for free. I'm sure you don't work for free. In many case, if the concern isn't present at the time I inspect the vehicle the customer can bring back when concerns are present and I will retest for free. If the concern is normal for this vehicle then you are on your own. There are many aftermarket shops out there that will charge you less per hour but just keep selling you parts untill something fixes the concern. In the long run the Ford dealer would have been less to begin with. I hope you put trust back into the dealer, after all they have a name to uphold.
