Then my second choice.
I have an electronic leak detector.
Can't give it a real high recommendation because it does give off false possitives.
After forcing myself to use it for a while, I've finally got a 'feel' for it and it works pretty good.
My next choice is liquid leak detector.
UV Dye is next on the list.
Other than that, its pull the evap coil time pressurize and submerse it in water.
Overall, I love the ultrasonic.
It has its goods and bads though.
Bads..... hard to use in noisy areas.
Wait a little while after you just shut a system off, or you will hear the pressures settling down.
Goods.... mine paid for itself the first time I used it.
found a leak out in the middle of a coil really fast.
Its alot faster to use, you can wave the microphone across the coil and fittings way faster than an electonic leak detector.
Crank the volume up when a homeowner is hovering around.
They are real impressed when they hear the leak too and see the noise level bars going up. They like to be the ones to say, 'THERE IT IS' as if they found it hehe.
A happy customer is alot easier to tell the price for recovery and repair. Especially after 'they found the leak' hehe
Oh yeah, if I suspect a system is low, the first thing I check is the valve cores before I connect my gauges. You can hear them leaking real good when they go bad. My electronic gives false positives around valve cores too much, so I dont' trust the electronic around valve cores.
My very next purchase is going to be a D-TEK. I'm just plain sick of dealing with the TIF that I wasted my money on. I am personally opposed to having anything in a system other than refrigerant and oil.