Automotive Air Conditioning Information Forum

(reposting in correct place)

First time poster, first time AC install (1974 Fiat).

I have everything installed (except electrical relays), pulled a vacuum and I have a leak that is noticeable in the manifold gauges after just a few minutes. No R134A or dye or anything except the new compressor’s oil charge is in the system; all components are new.

I happen to have a tank of argon/CO2 (MIG welding gas) that I think might be an OK subsitute for nitrogen.

I bought a nitrogen regulator since my welding regulator is calibrated in cu ft/hr but the one I bought looks like it is intended for home HVAC use. The manifold gauge set is the typlical R134A setup.

Is there a way to feed the hose from the regulator (which I could adjust to 125PSI) to the manifold guage set? And is this a good way to find leaks?

Specific products that I have:

YESWELDER Nitrogen Regulator with Hose,0-600 PSI and 0-4000PSI Output Pressure,CGA580 Inlet Connection and 1/4" male flare fitting (Link removed)

Four Seasons R134a Aluminum Fahrenheit Manifold Gauge Set w/Coupler - 59199 (Link removed)

Thanks!

MikeR (Portland, OR)

The 1/4 male flare on that regulator should mate with an R12 charging hose.

Two things to remember about using CO2 for leak checking:

It is a refrigerant gas. So while you can pressurize the system to 150 psi and check for leaks with soapy fluid, a leakdown test will be affected by temperature just like any refrigerant.

CO2 will not set off an electronic leak detector. So if you plan to use an electronic detector, evacuate the system first. Add 2 ounces of 134a, then pressurize the whole system with your CO2. So the escaping gas will have a trace of 134a to detect.

bohica2xo wrote: ↑Sat Jun 08, 2024 11:58 am The 1/4 male flare on that regulator should mate with an R12 charging hose.

Two things to remember about using CO2 for leak checking:

It is a refrigerant gas. So while you can pressurize the system to 150 psi and check for leaks with soapy fluid, a leakdown test will be affected by temperature just like any refrigerant.

CO2 will not set off an electronic leak detector. So if you plan to use an electronic detector, evacuate the system first. Add 2 ounces of 134a, then pressurize the whole system with your CO2. So the escaping gas will have a trace of 134a to detect.

I hope my leak is large enough that I'll hear it or be able to see it with soap bubbles.

I see a zillion charging hoses marked "R12" in various colors... are they all the same?

Would the setup be to connect the regulator to the R12 charging hose to the low or high side port of my system which has R134a ports? Or would I connect the regulator to the R12 charging hose to the manifold gauge set to the ports on my system?

Sorry for being so thick.

If you have a set of Service Port Adapters for R-134a with 1/4" flare fittings where the hoses attach (pictured), an R-12 hose with 1/4" knurled flare (female) fittings on each end will screw right on.