Tiny leak from valve core on low pressure service port on new mini split?

[gamp945]

Hi all,

I just installed my first mini split. I tried to do it by the book with all the right tools and procedures, including a nitrogen pressure test and triple (quadruple, actually) evacuation.

The tests went great (300PSI pressure, 125 micron vacuum) and I released the refrigerant.

The final step was to re-insert the valve core into the service port with my core removal tool. After inserting the valve core, I put "Big Blu" leak detector on the 1/4" port and opened the core removal tool's ball valve as demonstrated here:

When observing the leak detector I believe I found a very small leak because I could detect some bubbles forming. I thought that maybe I did not put the valve core in correctly so I removed it to try again. When I removed it, it appeared like this:



If you click on the photo and look at it close-up, you can see that there appears to be a flaw in the clear rubber (?) gasket component - kind of like a small "hair" coming off the bottom. Do you think this imperfection would cause a small leak? Any advice on how to proceed? I'm thinking that I should buy a replacement valve core and hope that the problem was just that the original is defective. But how do I find the correct valve core - or are they all the same?

For now, I have left the valve core removal tool attached and have the ball valve in the off position to hopefully contain the leak while I figure out what to do. Thanks for any advice!

 

[The Cobbler]

I know very little about refrigeration, but it seems like an easy and inexpensive attempt at a repair .

 

[Snapped-off]

Try a new valve core.

 

[fitter30]

Cores are all the same except some automotive. Refrigeration supply companies might not sell to you. Looked a Auto Zone but they wanted $19. Call other auto supply or appliance parts. Might have to buy a pack of 5.

 

[pcmeiners]

When you install the new valve core, put Loctite blue on the king valve's cap's threads.

 

[danski0224]

When you install the new valve core, put Loktite blue on the king valve's cap's threads.

You don't need that ****.
Nylog is just fine.

 

[PopcornSutton]

This might sound dumb, but are the port caps the brass ones with the gasket in it? If not, that might be enough to hold the leak. Lot of techs immediately toss plasic caps and put the brass ones on.

 

[pcmeiners]

T

You don't need that ****.
Nylog is just fine.

That is OK, you use a modified oil, I will use Loctite, a sealant specifically for threads.

 

[gamp945]

Thanks for all the advice guys.

Looks like refrigeration valve cores are all the same size. It seems like there are differences in the gasket material but the vast majority are made of Teflon. The gasket colors (clear vs. blue vs. black, etc) don't seem to indicate anything functional. I'm buying these Made-in-USA ones:

https://www.supplyhouse.com/CD-Valve-CD3800-Plastic-Storage-Container-for-Valve-Cores-w-Wrench-Tool-and-Thread-Chaser-Includes-6-Valve-Cores

From some googling, a lot of pros say that service schrader valves are a major failure point and the real seal comes from the valve cap. My mini-split did come with with a brass valve cap, but it does not have an o-ring. I'm buying a pack that includes o-rings:

https://www.supplyhouse.com/CD-Valve-CD2245-6-1-4-Flare-Brass-Cap-Pack-of-6

 

[chinboys]

Most or many of the mechanical fittings used in HVAC-R are designed not to use any sealants.

For instance, using the refrigerant's respective "oil" for the properly flared metal-to-metal connections and the right amount of torque will make solid connections.

Just watch how much torque you are applying to the new Schrader valve when using the core valve tool and test it afterward for leaks.