I was told by older tech I work with that you can't use dyes on residential air conditioners to help locate leaks in the system. I'm just wondering if he is full of bs or this is true?
I say BS. I use them and they're great, you still need a sniffer for the areas where it's just gas but combined you'll have no problem finding any leak.
This is what I use http://spectroline.drupalgardens.com/node/1221
I have a yellow jacket sniffer, but I find it useless sometimes because it has so many false alarms. So I usually just pump up units full of nitrogen and soap everything to find the leak. But sometimes that doesn't even work and that's why I wanted to try the dye.
I've really lost faith in using nitrogen to pressure test AC systems. I have pumped 300+ psi of nitrogen and see no signs of a leak yet at the same time can soap the schrader valve on the a-coil and see it leaking.
Dye is too messy and I have never used a sniffer. I just look for signs of oil. I believe the best way to leak check is using a vacuum pump and micron gauge.
finding the presence of a leak i have no problem, i usually do the vacuum gauge thing, its pin pointing where the leak is that is troublesome sometimes, and maybe using the dye could help me when i cant seem to find where its coming from. Also is it possible that the A-coil is only leaking in the summer when it gets heated up by the furnace??
Sometimes the best method of leak detecting is persistence. One way is not necessarily better than an other depending on the circumstances.
I honestly have to say the best method I've found is ultrasonic....problem is I can't afford one.
Ultrasonic... Sounds expensive!
http://www.professionalequipment.com/ultrasonic-leak-detectors/
Looks like the price ranges from $400 - $3000.