AC hose question

If they are still the original hoses, now is the time to replace them. Pressure test or not.

If they have been replaced, was an old-school R-12 hose used, or were they upgraded to the newer 'barrier' hoses needed for R134a.

In either case, how old are the hoses.

To your question, I'm sure you could cobble something together with some fittings, a gauge and a schrader valve to pressurize each hose and let it sit overnight to see if the gauge reading goes down.

Air compressor air can tend to be humid, not something you want to introduce into an AC system. Nitrogen would be best.

In any case, you will need to install a new drier, always needed when a system has been opened to air.

Thanks, they are probably 7-8 year old R-134a hoses been off the car about 6 years stored in the garage. I have a new drier on order

As a follow up would a "cobbled" vacuum work which wouldn't put any moisture in the lines?

quote:

As a follow up would a "cobbled" vacuum work which wouldn't put any moisture in the lines?

Your hoses should be fine.

And sure, checking for leaks with a vacuum is what an AC tech does with an assembled system. But unless your compressor air line is spitting water, pressurizing would be fine. Just wanted you to be aware of the moisture issue and treat accordingly.

One hose runs at up to 300 psi while the other runs at 50. So pressure-testing probably should be done accordingly. Both are routed pretty close to the right header and cook nicely to a bricklike consistency over time. Trust me- even the low pressure hose will blow at the most inconvenient time- like when you're laying under the compressor adding freon! Did you know that old compressor lube stains your face & hair? Seen it happen....

Replace old hoses; r-134a conversion hoses will fit R-12 systems with adapter fittings. The later hoses have a barrier layer inside and o-rings on the ends, and do help to keep the outrageously expensive R-12 inside longer. Do NOT replace your flair fitting hoses with regular aeroquip; the ptfe inside also leaks freon right through the surface. Aeroquip makes special barrier braided-stainless for bling-fans; I think A/C fittings use a 45 degree flair angle while regular aeroquip fittings are 37 degrees, for even more leak opportunity.