I had my aircon checked and recharged about 2 months ago and it was all OK and it seems to have emptied again where is the drain valve I can find the inlet at the top left by radiator can,t find the second which I presume is the drain off. It keeps ticking like something is cutting in I assume this is to do with the aircon.. Gary
There isn't a drain valve on aircon systems, what are you trying to do, fill it up yourself? The ticking is probably the compressor cutting in and out due to low pressure.
The answer is no, there is no telling where the leak is, that is what the dye is for. Also no you cannot refill the aircon gas unless you have the actual machine (which costs thousands) + there are strict government guidelines as to not letting it escape into the atmosphere.