Anyone work with Home A/C 410a? Need input..

[Gnx6]

What a day to find out my A/C is low on charge at my house. 79 degrees in my sons room (16 months old). I ordered 410a and pressure gauges from amazon. Just need some input, anybody work with 410a Home A/C systems?

I work on car A/C (R12 and 134a) so I'm sure I can figure it out. Just wondering if there are any pressure charts online? I know I am looking for a 20 degree split, discharge is 20 deg cooler than inlet register duct and High side should not go over 200 or it will stall the compressor. Any other key points?

Where is a good place to find a dye charge online and is that superseal stuff any good? If so where is a good place to find it? Thanks!

 

[Bescurred]

90% of the time if you are losing freon, its coming from the coil inside the house on top of the furnace. That leak fix stuff doesn't work. I did home ac work a long time ago but haven't really worked with 410a. Time to probably find a buddy that does side work if it is the coil. It's a really easy swap out and takes less than an hour.

 

[Gnx6]

Sweet! Thanks! Other thing is my unit (compressor) is not bolted to the concrete pad so I had suspected there may be a leak at one of the connections out there. Just want to top it off and deal with it when I have time. Thanks!

 

[turbo87adam]

The proper way to charge your a/c is to charge it by adjusting the subcooling wich is essentially putting enough refrigerant in the system so it start to hold back in the condenser to remove heat out of the refrigerant in its liquid state. In order to adjust this you will need to take the pressure reading on the high side of the system. Look at the guage next to the pressure reading there will be a temp reading for that pressure take that reading and compare it to the actual temperature of the liquid line( smaller of the two lines) the liquid line should be a lower temp than the pressure / temp on the guage usely the condenser will have a subcooling specification on the I'd tag on the outside unit example if the high side pressure is roughly 350 psi the temp coralation would be 107f and your liquid line temp was 92f you would have 15f of subcooling remember r410a is a high pressure refrigerant so where hand protection when removing guages on high and low side. Also note make sure to purge air out the hoses on your guages before charging and also when charging system with liquid refrigerant into the suction side of the system just crack your suction knob a little bit because if you flood the compressor with liquid refrigerant it will due too things it will wash the oil out of the compressor and can damage the valves in the compressor because it trying to compress a liquid instead of a gas state of refrigerant and stop a little bit at a time to allow refrigerant in the copper line to even out in temp.

 

[turbo87adam]

Oh I forgot to mention a lot of the times they will leak at the to brass access caps where your guages go and at the expansion valve flare connections in the inside air handler. Pretty much check all mechanical connections first and u can use bubble soap on these connections to verify leaks and verify the leak has been repaired as well if you do not have access to a refrigerant leak detector.

 

[Gnx6]

Great info thanks! I have a Matco leak detector and it said in the instructions it can do 410a.
These are the guages I ordered:
http://www.amazon.com/gp/product/B003FNQNQ4/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1

Is there a pressure chart vs.temp online I can use for reference?

 

[Gnx6]

I hope like heck that the fitting on the yellow hose is correct and will thread onto the cyl. (Refrigerant can)

Scott

 

[Gnx6]

Found this for 20 bucks, will take the guesswork out of the noob factor...

http://www.supercoolsliderule.com/

Glad you told me to add slowly, cause I would do like I did with R12 and just pour the coal to it.. (Open the valve right up). Ideally I need a new unit and furnace (Even though the one that was in the house when I bought it was only about 5 years old). When the system was properly charged on a 98 deg day it could not get the house below 75f. I think it is too small for my application.

 

[turbo87adam]

You can google temperature pressure chart for r410a and find a t/p chart. Automotive style hoses usely use a SAE style connection at the service end of the hose where as all other hvac/r connections for service end of hose are NPT you will need a guage set dedicated for r410a systems because operating pressures are typically twice as much as standard r22/r407a system for residential use. The subcooling calculator should work fine for your situation I would clean both evaporator and condenser coil with a diluted simple green solution and change the air filter before charging system to ensure proper operation of system when completed. One last thing I would mention is whenever cleaning or servicing( taking any panels off of unit )to turn power to unit off I say this because I've been in the HVAC/R trade for 11years and I myself get complacent with this simple safety precaution. Also if you think your system is undersized for your house you should have heat load calculation done to determine how many btu's of cooling you need for house and have them check your ductwork to ensure it is properly sized as well. this plays a key factor on the efficiency and comfort ability of your A/C system.

 

[6cylboost]

charge to subcooling on txv. charge to superheat if piston(accurator)

 

[Gnx6]

Are the threads on the 410a cyl the same as the compressor? I know it's the yellow hose but when cyl shows up I want to charge system, not wait for more peices..

 

[turbo nasty]

X2 to the above advice ....charge for superheat for tev/txv and charge for subcooling of fixed restrictor (cap tube, orifice, etc).

 

[6cylboost]

24.8 (30#) jug will have 1/4" fitting on it. when the 410a mini splits came out, i think u need a 1/4 to 5/16 adapter but not on home units or jug

 

[Gnx6]

Ok, so I got all the stuff last night and charged it up. Found out the hard way my Robinair gauges leak on the low side. There is some kinda shuttle valve in the gauges so they will not register unless you ave the cyl hooked up to the yellow line and the tank valve open. The low side started to get frosty so I know it was charging when I did not want it to. I shut the valve on the tank and had the wife shut off the ac in the house. Figured out what the hell was going on and cranked down the low side fill valve on the guages some more. Re-connected everything and tried again. Compressor got louder and hit the high pressure cutoff. Guage hit 600 psi on high side. I purged the system down so it was at about 475psi. On the side of the machine it said optimal working pressures were 550 and 200. I had it at 475 on the high side and 105 on the low but it was only 65 degrees out.

There was a good amount of heat coming off of the condenser and inside the house the inlet air temp was 73 and the outlet ducts measured between 47 to 51 depending on where I was in the house. The high pressure liquid line was not hot like they typically are on a car. So I know that I overcharged it due to a leaking low side fill valve on the gauges. My question is if I am sitting around 500 psi on a hot day is that good to go or still a little high? I did get one of those sub cooling charts but what threw me off was that my liquid line (high side) was not that hot which I am guessing means overcharged slightly?

I did not look inside the case for a txv but I figured since my pressures were way higher than an orfice style on the chart that I had txv.

What do you A/C guru's think? Thanks!

 

[turbo87adam]

Your pressures seem off did you clean both evap and condenser coils and verify air filter isn't restricting air flow? I'm almost 99% sure your system being r410a has a txv so you will need to adjust the sub cooling on the system as I have explained in previous posts. Your pressures are probably off more because your charging at night when you don't have as much of load on your system so your txv is throttling down because evap coil is cold. Causing a lower suction side pressure and a higher head pressure!!

 

[6cylboost]

335 head 12o suction would be closer but now your starting to scare me. thats a high pressure refrigerant so be careful. if u dont get it right u will be paying for it. 610 should be what high pres saftey trips at and thats if it has a high press saftey.

 

[Gnx6]

Yes, high pressure did cut off around 600. Air filter is clean, (it is a WEB washable filter). I did not clean the coils like a lazy poop. I will do it on the weekend, I work 4-10hr days so I don't get home till about 7:15 pm. Seems to be cold and compressor is not noisey so I think I am in the ballpark?

 

[GNONYX]

I hope this chart will help you out
We had some hail storm that damaged both of the AC coils fins and replaced all components with 410a units.
According to the AC tech. this past January r22 is being phase out, and the replacement will be with 410a, but you can still get r22 with now some additional cost then standard.

 

[Gnx6]

Pressures are much better. After cleaning coils they are 400 on high side 190 on low. Blows cold as heck and compressor sounds happy. Good heat coming off of condenser with compressor on.

Scott

 

[GNONYX]

Hi Scott, I glad you got it to run cool
Now remember every year to clean the coils and fins