DIY R410 Residential work

Who has any general advice for topping up a residential R410 A/C only (no heat pump) unit? I’ve perused quite a few videos and have a business partner (in the medical business) who does his own at his home and a few other places who has convinced me to do it.

Besides the basic protocol for calculations, monitoring pressures and temperatures I’m wondering about the best time of day to do this?

Any thoughts?

No disrespect intended for those who really are experts at this but I’ve got 3 units to do and at around $225 for these supplies I’ll give it a go to save $1000.

@TBJK knows what’s up in this field.

#1 Are you sure you are low? If you are low, have you looked for & found the leak?
#2 Are your filters clean, coils clean?
#3 Get quick disconnects, your fingers will thank you.

You do need to know what your metering device you have. That matters in how you charge it.

#1 - ‘pretty sure’ - been years since any service was done and that was it last time. Not prepared to detect a leak at present.
#2 - filters cleaned. coils on each end are clean. I recently power washed the compressor side - generally was pretty clean - symptom - failure to reach cool temp with this cool weather.
#3 - can you send a reference to the right ones? Not finding a set. Looks like I have screw connect, schraeder connector and I’m seeing a variety of HVAC quick connect references - some seem to be specific to automobile. My hoses are schraeder screw end so I guess the connectors would have to be schraeder valve to scraeder quick connect. I’ll take photos later. Gotta run for now. I’d be willing to wait and get some!

On a roughly related side topic… do these kits generally have oil already? In other systems, the coolant is “virgin” and oil must be added in the proper amounts.

https://www.amazon.com/Yellow-Jacket-Quick-Coupler-Loss/dp/B01M0KJLZK/ref=asc_df_B01M0KJLZK/?tag=hyprod-20&linkCode=df0&hvadid=344108663927&hvpos=1o3&hvnetw=g&hvrand=1108039642357537804&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9026828&hvtargid=pla-759843769866&psc=1&tag=&ref=&adgrpid=70729706793&hvpone=&hvptwo=&hvadid=344108663927&hvpos=1o3&hvnetw=g&hvrand=1108039642357537804&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9026828&hvtargid=pla-759843769866

Your discharge pressure will vary on your condenser, mainly the seer rating & condition of the condenser. Rule of thumb for normal is about 30 degrees above the ambient saturation temp. So at 100 degrees day about 477 psig

You dont add oil to them generally speaking…

Thanks, TBJK.

Here is what my hoses have. They terminate with this connector and have a moveable collar that screws down over about a 3/8" OD (but might be called 1/4") male thread onto an internal schraeder valve.

https://photos.app.goo.gl/UntjWK6bvykDVE3z7

You will want to get the quick connects. When you pull them off you will shoot all the liquid that was in the hose from the liquid line. The quick connects will allot you to remove the lines with minimal loss & then you can suck it back into the suction side of the machine, ridding the line of liquid refrigerant. Make sure that when you hook your hoses up that you purge the air out.

Interesting. . . I see the ‘quick connectors’ with the 1/4" thread adapters but no hoses available that terminate in a 1/4" thread. Here are both ends of my hoses. Maybe if I chopped up my hose and added a 1/4" adapter, then I could add the quick connect. But that takes proper equipment.

Seems strange that I don’t see hoses that terminate with anything other than a press fitted schrader adapter that I have. What are they expecting those quick connects that you reference will go onto?

That is, I guess there are HVAC hoses available to accept the 1/4" M end of the quick connect but I’m not seeing any. Yes, I can see how you would lose all the liquid in the line. Perhaps the suction side could suck it back into the system before disconnection. Then, as you mention, there is the problem of air in the line since my hose is open to air. I thought perhaps the schraeder end of my hose was sealed until connection, but no, I can blow all the way through the hose as it is.

How is your rig configured? Did it come with quick connect or did you have to have custom hoses to 1/4" F fittings then buy the connectors?

Don’t chop them up. The fittings will thread right on them. 1/4” male flare to 1/4” female flare

Oops! Thank you! You are right. I’m just now realizing that. :slightly_smiling_face:

But . . . Those female connectors at my hose end are 5/16 and the QC adapters are 1/4" M x 5/16" F

So, sounds like I’ll be trying to go from 5/16" F to 1/4" M ?

BTW, thanks for all the help!

I have yet to use these myself, but it looks to me like the basically have their own schrader valve, so that when they are unscrewed from the system and it’s schrader valve far enough, they close, retaining the liquid in the line, so you can ease it back into the low side through the gauge set after the high side is disconnected.

That’s what I thought, but the yellow hose as I showed above (and the others as well) are not sealed. That is, I can blow air through them easily. It does look like they have an internal schraeder but I think that is just a tab to depress the valve core on the schraeder on the A/C unit.**

Correct, the standard hoses just have a tab to depress the schrader valve in the unit. These adapters add the valve for convienience and refrigerant retention. You can also get adapters that also still go 1/4 flare to 1/4 flare, but with ball valves instead. They both accomplish the same goal of attempting to retain as much refrigerant in the system as possible, and minimize the drift in the mixture of the two components in the blend.

The amazon one I linked is 1/4” on both ends. Standard size in our industry are 1/4, 3/8, & 1/2”

When you do have to add refrigerant, be sure to add it as a liquid into the suction line. Do not add it as a vapor as you will get fractionation. As a friend of mine found out the discharge pressure will not be stable. It will have wide swings and then the full charge will have to be replaced.

Back to the metering devices.
You have TXV’s which you charge by subcooling.
Then cap tubes which is charged by suction super heat.
Flowrater you charge by suction superheat.

All charge needs to be checked at or about design conditions. Not with an 85 degree house. The pressures and temps will be off.

2 Likes

Also you need to be sure that your unit is R-410a. There was R-407c which was used as a replacement for R-22. It was a bad blend that if you lost part of the charge you would most likely have to replace the whole charge since the temperature glides were so far apart.

1 Like