AC leak test options?

[PNWYukon]

The AC has been out for a while and we had the schrader valves replaced, which did nothing. Can anyone recommend a way to locate the leak in the system aside from going to a shop?

 

[Cbncanada]

The Yukons commonly develop a leak in the lines going to the rear AC unit. They rust out along the frame. I just disconnected the rear and plugged the lines. I live in a climate where the rear AC is not needed.

 

[OR VietVet]

What Les said. You can get inexpensive wand sensor equipment that sniffs for the leaks. You can do a sight check and if you see an oily dirty spot on a connection or line, that is a/c oil leaking out with refrigerant and leaving the dirt smudge. They also used to check for leaks with a flame and if there was a leak that went in to the flame it would be a green flame. Way old school. Like me.

 

[PNWYukon]

Thanks, I will check that, but down here we don't have the rust issues.

 

[OR VietVet]

Thanks, I will check that, but down here we don't have the rust issues.

I am in Eugene, Or. No rust probs here either.

 

[SnowDrifter]

No rust doesn't mean no abrasive wear or degradation of soft parts.

UV dye can be hit or miss

Sniffer well tell you a lot

As will airing it up to 200psi with nitrogen and going over areas with soap water.

How much does your shop charge for leak hunting? Pending that, you might find yourself working far too hard for a one off. You need to go through the whole system. Finding a leak in one place doesn't guarantee there isn't one elsewhere too.

And this all hinges on your issue being caused by a leak

And with everything else, if your system has been pressurized for a while, aside from the standard vacuum to purge air, I would HIGHLY suggest replacing the desiccant drier at a bare minimum. And if you are able, flush the oil of the system and replace with new as well. The oil a/c systems is, like brake fluid, hygroscopic. It absorbs moisture. This is by intent. However if there's no refrigerant in there to guarantee moisture physically cannot ingress to the system, you're rolling the dice on if it's still good or not

 

[PNWYukon]

No rust doesn't mean no abrasive wear or degradation of soft parts.

UV dye can be hit or miss

Sniffer well tell you a lot

As will airing it up to 200psi with nitrogen and going over areas with soap water.

How much does your shop charge for leak hunting? Pending that, you might find yourself working far too hard for a one off. You need to go through the whole system. Finding a leak in one place doesn't guarantee there isn't one elsewhere too.

And this all hinges on your issue being caused by a leak

And with everything else, if your system has been pressurized for a while, aside from the standard vacuum to purge air, I would HIGHLY suggest replacing the desiccant drier at a bare minimum. And if you are able, flush the oil of the system and replace with new as well. The oil a/c systems is, like brake fluid, hygroscopic. It absorbs moisture. This is by intent. However if there's no refrigerant in there to guarantee moisture physically cannot ingress to the system, you're rolling the dice on if it's still good or not

Yes, it has been depressurized for some time. No doubt that it is contaminated. I was hoping it was a simple find and fix, I definitely don't want to shoot the parts cannon at it. It was checked out by the "AC man" recharged and worked for about a month, then lost all the charge "somewhere". That led me to believe it was not a catastrophic failure but a leak point of some kind.