A/c
 

I have a 1995 Corvette and about every 3 years I loose Cool Air and need to refill. Have a very slow leak any one have any idea how to find or where leak nay be?

I would first start with a visual looking for any greasy condition at connections. This would tell you an o-ring is leaking. Those things are 24 years old.
You can use a can with UV dye in it and a blacklight.
Check out the below video and let us know if it helps.

I used this product, It worked great for me only I used some kinda yellow glasses

My leak kit came with the glasses and a UV penlight. Used it on another car. Turned out the problem was the valve in the fill port. You could see it spewing the fluorescent dye.

Used one of the valve core tools that swaps the valve without draining the system.

If you have a leak and the leak dye things don't work (I've never had one work) then put a vacuum pump on it and listen for leaks (wishful thinking) or if all else fails replace the o-rings until the leak is gone (this is the only sure fire way to fix it). Either way you will need a vacuum pump. The 1 caveat is if the leak is at the Schrader valve your connecting the pump to then you will never find it so if at the end you still have a leak change the port you vacuum from to check the valve. If it's been leaking for years it's very likely when you take the suspect joint apart you will see corrosion inside, which must be cleaned up before fitting a new o-ring. I would actually start by replacing both Schrader valves and checking for leaks. It's the easiest and cheapest thing to do since you have no idea where the leak is.

I think you can get a loner halogen detector from Auto Zone and the like. It will alarm when the Freon is detected. If it is in the area where the evaporator is contained, I am not sure of the detection of a minor and slow leak.

A leak that slow should probably be left alone. I would let it get worse.