Question for A/C Experts

[eleven14]

I replaced my evaporator core and condenser last night and pulled a vacuum on the system for an hour then monitored it for an hour and it held fine.

I left the A/C gauges attached overnight and, about 9 hours later, am showing a slight drop in system pressure.

Last night / this am readings:

I’m hoping to button things back up today but am unsure if this is abnormal (ie: A/C gauges naturally lose some pressure via schrader valves, etc.). In hindsight, I should have removed the gauges and rechecked pressure again this am.

Thoughts on this? I cringe at the thought of replacing the evap and condenser again, but would rather do it now if this system is compromised. Thanks in advance

 

[bmorey]

I just recently had some trouble with an AC line getting rubbed by my hybrid winch bumper, so I rented the same manifold gage set and vacuum pump from Autozone.

I would be fairly confident that your system is fine and is holding pressure well. Considering all the fittings and hose connections and that manifold gage, there are a lot of little areas/connections for that pressure to slightly leak down.

If you are really worried, maybe adding a bottle of that leak detector dye wouldn't hurt while you replace the R134A refrigerant. This way, if you do have a tiny leak in the future, you can just grab a blacklight and find it pretty easily.

Just my take on it!

 

[Syr4RinNC]

The pressure will also change based on the temperature. Higher temp more pressure, lower temp, lower pressure. I dont know how much temp variation occurred over this time. I think you would have had a more significant drop with a significant leak

 

[eleven14]

The pressure will also change based on the temperature. Higher temp more pressure, lower temp, lower pressure. I dont know how much temp variation occurred over this time. I think you would have had a more significant drop with a significant leak

We probably had a 20 degree swing overnight. This morning I mistakenly disconnected the lines with the valves open, so re-pulled a quick vacuum and monitoring.

Assuming I didn’t damage anything with my disconnection shenanigans and the system holds, I’m leaning towards buttoning it all back up and calling it a day unless someone with more experience than I can definitively say different.

Appreciate the responses guys

 

[eleven14]

Update

It held perfectly for 3.5 hours but when removing the coupling from the low pressure side, it releases all pressure.

Gonna replace the Schrader valve and will report back, hopefully that's the solve and also a reason for the minor drop in pressure overnight.

 

[eleven14]

To close the loop on this, I figured out that the cheap rental AC gauges I was using were torching the schrader valve on the low side when fully opening the attached coupling, causing the failure.

The solution is to only open the low side coupling halfway and it was fine once I installed a fresh schrader valve. Hopefully this spares someone else the headache of a trip to the auto parts store.

Also, I struggled to find the actual valves required online but can report the package below was a perfect match for the OEM valve I removed. Bought at O’Reilly.

I also had to buy a cheaper set to get the valve removal tool but those valves looked different/cheaper than the OEM.

 

[rwh963]

someone needs to inform Evertough that "RETARD" is definitely not politically correct!

 

[meltdowner]

someone needs to inform Evertough that "RETARD" is definitely not politically correct!

Political correctness is censorship. Not in the USA pal.

:50cal:

 

[Drcoffee]

Anytime you connect those gauges you need a light touch. Its very easy to damage the valve on the low and high lines. Stop once you feel resistance.

And while the system is open, replace the schrader valve, and add some dye.