Been looking at some videos like ones from Scanner Danner and wonder if it would be of any use. I had multiple instances where I vacuum the system for 15 minutes and then let it rest another 15 minutes and check the gauges to see if they have dropped indicating a leak. No they haven't dropped so I continue the vacuum an hour or two and recharge. Then a week later find the charge has leaked out. Would the micron gauge be helpful in showing a leak too small to detect with the 15 minute rest test?
Anybody here use a micron gauge during a/c work?
- Thread starter atikovi
- Start date
I flush and pressurize the system with 150 psi nitrogen. If the system holds pressure for 24 hours, I release the nitrogen and vacuum the system down to 250 microns. If the system stays below 500 microns for five minutes after I valve off the system and turn off the pump, it's pretty sure it is tight. I then turn on the vacuum pump for another 30 or so minutes to get out any minute amount of moisture before charging the system. Maybe overkill but dealing with a leak after charging the system is additional work and expense.
Those gauges will not show a leak in the schrader valves. And is probably where your leak is.
New Schraders on a repair are ALWAYS money well spent.
JHZR2
Staff member
Nylog on the schraders and cap threads supposedly helps.
Ive read that vacuum doesn’t show all causes of leakage, therefore a pressure test is also prudent. I don’t have a micron gauge, or do I have an alternative bone dry gas, so I use HC refrigerant in certain cases. Has worked well for me…
I'll probably get the micron gauge, but after watching this Scanner Danner video, (there is also a part 1 if you want see all of it)
I decided to start with nitrogen testing. Got this Uniweld regulator made in USA off Facebook for $50 and a filled 20 cf tank from a local supply house for $115.
What pressure should I test too? Like 150 psi? The low side never gets that high so I don't want to blow something there. Any idea how long a 20 cubic foot tank should last? How much volume is there in a system? Maybe less than 1/10th of a cf, multiplied by 10 times atmosphere = 1 cubic foot per test?
Micron gauge shows how deep a vacuum and if there's moisture in the system. Can also be used to see how tight a the system is.
When the system is turned off, the low and high equalize at a static pressure, should be equal to the saturation pressure of r134a. That pressure would be about 125-psi on a 100°F day. 150-psi is static pressure at 112°F.
So 150-psi seems pretty reasonable to me.
