94 Accord A/C fan

My A/C will not hold a charge for more than 5 days. I took it to a mechanic and he told me the A/C Condenser fan did not work. After informing him that the fan worked and the a/c clutch kicked in when I added the coolant myself, he told me that it actually does work, but only when he "did something do it". He then said the A/c condenser fan is possibly an intermittent problem. He claims the fan relay is bad and wants to charge me 150.00 to replace it, then he wants to charge 240.00 to put dye into the system to see if there is a leak. Is there a better way to test the fan relay aside from turning on the A/C and visually confirming that it works? Or would me simply replacing the relay be best, then check for leaks? The mechanic claims that the fan relay HAS to be replaced and dye put into the system before he can do any further diagnosis. I understand about the dye, but this issue about the relay seems questionable to me. Also, he tells me that the A/C Condenser fan should be on all the time when the A/C is running. It is my understanding that this fan only turns on when the condenser gets too hot. Any help would be greatly appreciated as I can't afford to waste $$ on this one.