Thread: Basic leak testing of used A/C components and systems

100% doable!!

Obviously we use nitrogen in the trades for pressure testing, but argon will work, the hardest part is making the adapters.

I'd use at least 250psi in the condenser, probably only 100-150 in the evap.

Plunge into a tank of water and check for bubbles.

The big issue is the oil in the comp.
It is extremely hygroscopic, it pulls moisture out of ambient air at a prodigious rate, and is cactus in a relatively short time. Think hours.
It'll need replacing before firing anything up.
At least the PAG oil used in car AC doesn't hyrolyse like POE used in commercial and industrial refrig does, all it does is hold the moisture.
Oh, and use a dedicated refrig flushing solvent for the major components and hoses before installation.

Many years ago when I was trained in automotive aircon installation and maintenance, the standard way to test a system for leaks when installing or recharging was to hook up the gauges and vacuum pump and evacuate the system, then leave it sit for several hours and see if it held vacuum per the gauge. A few years ago when I had a system re-gassed, I asked the tech if he would do this; his response was that he can't afford to have his gear sitting connected to a car for hours just to see if it holds vacuum. So I guess it is no longer done, but not because it doesn't work. I'm sure you could jury-rig a vacuum system to test your components this way.

Thanks Rick - great info.
Adapters shouldn’t be too hard - I’ve got a lathe and various taps/dies so should be able to sort something out.
I’ve also kept various hose end fittings so have those to measure or cannibalise.

I don’t have any gauges of the correct range that haven’t had oil etc in them - so will probably just grab a cheap service manifold setup off eBay and use that.

I figured that for just static pressure testing the Argon would be fine - knowing it would get expensive quickly if used for purging!!
Thanks for confirming it’s ok to use.

Steve

Originally Posted by POD

Many years ago when I was trained in automotive aircon installation and maintenance, the standard way to test a system for leaks when installing or recharging was to hook up the gauges and vacuum pump and evacuate the system, then leave it sit for several hours and see if it held vacuum per the gauge. A few years ago when I had a system re-gassed, I asked the tech if he would do this; his response was that he can't afford to have his gear sitting connected to a car for hours just to see if it holds vacuum. So I guess it is no longer done, but not because it doesn't work. I'm sure you could jury-rig a vacuum system to test your components this way.

I still haven’t got my head around the use of vacuum for testing complete systems.
My understanding is they get evacuated mainly to remove moisture, but obviously if they won’t hold vacuum then something is leaking.
But the system doesn’t run under vacuum - so there can still be leaks when it’s running even if it holds vacuum statically.
From what I’ve read, finding those leaks is typically done with a combination of the UV dye and/or a leak detector.

Steve

A vacuum test is a very good test,but not as practicle as a pressure test.

Rick’s advice is the way to go,being carefull that some leaks are very slow,won’t show a stream of bubbles in a water tank,only a bubble every so often.
And keep any water or moisture out of the components.

Also have a good look over the coils for corrosion,if any is present it may be better to replace them,as it will probably get worse,even if they are not leaking under the test.

Good luck with it.