how much leakage from a Schrader valve is too much

[msrichmond]

I bought a Harbor Freight sniffer. On its default setting, it goes from 'beep beep beep' to 'siren' when I check the service ports. These fittings are new. Is this a common problem? With the plastic cap on, I don't get an indication of a leak on the default setting, but when I take the caps off, I do. All of this is with the engine cold, I charged the system a couple of days ago.

Is there a specific protocol for testing these valves?

And if they need replacing, do the DIY tools work or do I need to go to a shop where they can recover the refrigerant, replace the valves and recharge?

[Cusser]

With the plastic cap on, I don't get an indication of a leak on the default setting, but when I take the caps off, I do. All of this is with the engine cold, I charged the system a couple of days ago.

Perfect !!!! The cap is the real seal, the schraeders are not the primary seal !!!

And if they need replacing, do the DIY tools work or do I need to go to a shop where they can recover the refrigerant, replace the valves and recharge?

From what I've read: the special tools do work. Watch the videos on YouTube. But you have no need right now for this !!!

[GM Tech]

That is how I test my leak detector- take off the caps and make sure it works...Then put caps back on.

[msrichmond]

Thank you!