Spent an hour or so trying to find the leak on a freezer which takes 404a. I beeped every fitting, and then up and down the evaporator and condensor. No indications at all, of a leak.
Today just for something to do, I tried the beeper (D-Tek, Tek Mate) on a jug of 404a. Loosen the cap, give a twist on the valve, and I can hear the gas hissing out. The beeper doesn't even whimper. Same on a jug of R-22 and the beeper reacts instantly. Back to my catalog, it says the Tek Mate detects CFC, HCFC, HFC, and blends.
What's going on? What to do about it?