HVAC

[zahc]

I'm pumping down a new air conditioner. The compressor is charged already but I'm pumping down the inside unit and the lines. It pumps down to 110 microns, but when I isolate the pump and hoses it leaks up to 300 microns in about a half hour. If I let it sit overnight, it leaks up to 1800. I don't know if this represents success or means there is a leak. Even if there is a leak it must be tiny so I don't know how I would find it. Should I let the refrigerant loose?

[JTHunter]

Check all of your joints, esp. soldered ones.

[zahc]

How do you actually check them? Without a helium leak checker I don't know how you could detect a leak so small.

I pressurized it to 300 PSI and left for 4 days and it only lost about 30psi, which could be within the margin of error or could still be a really slow leak.

[Nick1911]

Pressurize and check with bubbles.  Also your minor leak could very well be from your hose seals on your gauge set. This is very common.

[Jim147]

Yeah, soapy bubbles and is probably a hose. Like Nick said. That is my common problem.

[zahc]

I don't have any hose on my micron guage.

It goes R410 5/16 adapter -> 1/4" tee -> ball valve -> hose -> vacuum pump. The micron guage is on the tee with no hose. It's still possible any of the seals, ball valve, or micron gauge itself are leaking.

I'm going to pump it back up to 300 and test the flares with bubbles again.

[Jim147]

Flares? Is this a minisplit?

[zahc]

Yes it's for my garage and has two 1/4" flares and two 3/8" flares for the lines. I learned that some people solder the top ones, but I had no idea where to get 1/4 or 3/8 copper couplings, so I just flared them per instructions. I just pressurized it back to 300 psi and put bubble solution on the flares with null results. If it holds over night I will suck it down and let er rip.

[Nick1911]

If your flares check out under pressure with soapy bubbles, in my opinion, pull it under 500 micron go for it.  Vacuum is rarely held for more then the 5-10 minutes needed for the gauge to stabilize.  You're stabilizing at under 500 - I give that a green checkmark.

Your setup doesn't have a hose, but it does have seals based on rubber sealing against the flare service fittings.  Over time, they will seep vacuum in my experience.

The only thing that gives me pause about any of your readings is the 30PSI drop over four days.

[K Frame]

"I will suck it down"

Kinky. Remember, this is a don't ask, don't tell, safe space.