Troubleshooting with Superheat and Subcooling (TXV)

For more tips, visit our website, www.edgetekhvac.com.
To download a copy of our job sheet, visit our online literature library at: literature.nortekhvac.com/Unbr...

[@elttik]

You are a huge blessing to me with this information. I appreciate this tutorial very much!!! 5 stars.

[@cbzeej]

So far you've been the most informative HVAC channel I've watched. Just gotta slow it down a bit. Don't rush your words. But you're doing great! Keep up the good work!

[@raidone7413]

I thank God this is a KZbin video. That way I can pause and rewind haha

[@mr.saintman3202]

@@raidone7413 its not about that dude lol most ppls just listen to this while writing notes and sometimes the information can come in too fast or can confuse us more, pausing doesn't do anything lol he will still explain it the same way if you repeat lol

[@jayhvac4474]

Thanks for the great video! Just starting and trying to learn everything the right way! Just had a basic AC course this week and I learned a lot about how the system works. Looking forward to more of your content👍🏻

[@scottk0623]

Excellent job on the work sheet, thanks for making it downloadable for us. Great job

[@joselozano8499]

Been looking for this information for the longest . Thank you

[@Angelo-qz3qj]

Thank you, one of the best videos, if not the BEST

[@rudyvargas3547]

Thanks Greg very helpful video I watch this every day until this is stuck in my brain thanks a lot

[@tonyferreira6679]

Many thanks for the explanation,thanks also being só patiently,teacher,,Good blesh you

[@joellampaya2639]

Greg you are the best...thanks a lot man...

[@mrgreen9086]

Great video thanks for the different scenarios

[@htnowpro]

Great information and presentation. I also am trying to use apply this diagnostic information to automotive applications. Most of our systems use a fixed orfice and some use an expansion valve. But the fact of the matter is., Better diagnosis leads to clear and concise repairs. We do not use the super heat and sub cooling terminology or diagnostic and I wonder why. Seems like it would help. Thanks for sharing.

[@dannyobrien8468]

Great stuff!

[@sayitaintso1690]

Great info man!

[@viewmasters1]

Well explained. Great video. Would love a pdf of this diagnostic sheet.

[@davepenprase]

Good video thank you appreciated

[@conradviray5865]

Thank your sir 🙏

[@oleole2053]

I have an EPA 608 universal technician certification since 1994 but later went on to a career in Law enforcement since then, but still have a passion for HVAC, just wanted to say great diagram and breakdown for super Heat and Subcool.. oh by the way can u Please sent me copy for that amazing chart you are using.. Keep up the great work with tutorials. :)

[@carloscontreras8398]

Best video ever

[@mikefreedom5612]

Thank you

[@yusuflbs7535]

nice video.. but, can we use methode Superheat and Subcooling to troubleshooting HVAC system in vehicle?? thank you

[@jus1027]

What are your thoughts on a 410A system with a TXV inside and piston outside that has a low superheat and low subcooling?

[@justbeingreal5839]

Where can I find more scenarios like this? This is great

[@Tamilsongs2813]

TNX SIR

[@TheQv123]

Where can we get a electronic copy of that report sheet?

[@user-ko4pl6yk4m]

Is the sub cooling value fixed between 9-15 or does it change from one gas to another and from one air conditioner to another? thank you

[@cruzrobledo6631]

Great video. Where can I get a job checkout sheet?

[@davidmorrow95]

Hi Greg, loved video. Could you send me a copy of that system check list. That is a valuable tool.

[@ke6944]

Does this principle apply for a walk-in cooler?

[@bobwhitfield9491]

This is for 410a refrigerant for reference . I just double checked the numbers.

[@mark.r8900]

Hi, my r410a with txv unit. The suction saturation temp is about 33F and suction line temp is 48F giving 15F of superheat. But why is my liquid line saturation temp is 97 and my liquid line temp is also 97. I tried adding some refrigerant but nothing changes. This is a high velocity system air handler with a slab coil. I think my suction saturation temp is also too low. Both coils are clean and txv valve is new. Any help would be greatly appreciated. Thanks

[@garbamak000]

I had cxv with 20-plus degrees of temperature difference in Cooling and superheat as well as about 20 degrees difference across evaporator coil, I am thinking is a bad TXV the furnace is about 16 years old

[@user-bp8ef7ye3q]

Thanks for the video sir,but is this process applicable with HVAC that uses automatic expansion valve?

[@313astrologytv-7]

Thanks. What would cause low side reading to be good, but the subcooling on the high side to be very low?

[@EdgeTekHVAC]

Please contact our tech service team at 1-800-422-4328

[@mtbbiker6401]

Is it possible to be overcharged and still only have 1-2 degrees of subcooling? If yes, what might cause that situation?

[@mauichaui641]

I have a unit that shows signs of flooding txv and starving of evap. Unit originally was overcharged once I adjusted Freon these are the current readings. DT 15, Superheat 6, and Sub cooling 20. Unit specifies super heat at 8 degrees and txv design subcool 15. It seems to be smack dead in the middle of both. Previously the unit would reach retard on high side and have high suction temp as well. My last thought after looking at the system was someone had manually adjusted the TXV to get the sub cooling where they wanted it without thinking about filling condenser with liquid making head pressure seem to have nitrogen in the system on a warm day.

[@metalhalide4043]

If the TXV is set to 10 degrees Superheat is that when the suction pressure and airflow across the evap are in specific range? I thought the TXV will always maintain a differential of 10 degrees even if suction pressure or airflow fluctuate.

[@EdgeTekHVAC]

Thanks for the comment Superheat temperature is determined by the saturation temperature of the refrigerant in evaporator coil and the temperature of the suction line (either exiting the evaporator or at the suction line service valve).

[@jrdx]

Should add arrows on your schematic showing which why the refrigerant is flowing. And label your evaporator and condenser.

[@suncitykid915]

So having the same numbers for sh and sc is ok? I've been having trouble with troubleshooting units with sc and sh. Sometimes I get my sc but my line temp is high.

[@EdgeTekHVAC]

Please contact Technical Services if you need additional information.

[@PIndyJones]

What about 40 degree superheat. Within range sub cool at 10 (8 +/- 3). 25 degree td. Ambient 76. House 78. On a trane straight air gas furnace? Bad txv?

[@Keeping_it_Frank]

Hi. I tried this ac stuff as a kid and never really got any good at it. I now own a house and I blew the dust off my old tools and decided to check my ac. I feel like it’s struggling to keep the house cool. I live in Texas so arguably it may just be the way it is. I have a 5 ton Rheem. She’s old but new enough to use 410a. I hooked my gauges and everything seemed pretty high. Suction 128psig 50 degree Liquid 425psig 121 degree Ambient temp 97 f 20 superheat 23 sub cooling A strong 20 degree split with air as cold as 46 degrees (inside). Evap looks clean Condenser could use a cleaning but not bad I want to say it’s over charged but I don’t want to start playing around with it until I have a pro give me his thoughts. Any help would be highly appreciated. Thanks!

[@OnePointLander]

TXV or Piston?

[@Keeping_it_Frank]

Johnny N. TXV

[@OnePointLander]

@@Keeping_it_Frank Has the system always struggled? Or just recently? I would take a temp before the drier and after to see if you have a restriction there. Could be that system is overcharged or developed a restriction recently(drier, bad txv, kicked liquid line etc). Lots of variables though, we don't know your indoor return/supply/wb. If you have a clamp meter, you can also check the amp draw on the compressor to see high it is running above rated.

[@Keeping_it_Frank]

Johnny N. I’ll check the amp draw. I think it’s always struggled. Also for some reason it has 2 liquid line dryers. I’m thinking there’s restrictions their. Sadly one of the dryers is inside the condenser so I would have to recover the refrigerant with a machine and not the compressor. I do not possess that type of equipment. But those numbers are indicators of a problem?

[@OnePointLander]

@@Keeping_it_Frank Two perfectly working filter drier with neglible pressure drop shouldn't be a problem. If there was a restriction, common sense would probably point to the one in the condenser. On a 97-98 degree day here in Texas my pressures are 139/369 with a 21 degree split at the plenum. 64 Wb 78 DB return and 57 supply. SC is at 10 and SH is 11 with a TXV measured at condenser. I would temp the pressure drop before and after each filter to rule those out since you can do that easily. Then it might be txv and/or overcharge if the DFs are fine.

[@carlosjesusjimenezcanizale2793]

The superheat is the same for all A/C?

[@EdgeTekHVAC]

Hi Carols, it depends on the TXV. Our TXV's are set to 10 degrees, however this may not be the case for all other manufacturers.

[@kadariusbryant3271]

How can I get a copy of the sheet he is using?

[@BillyN31]

What about when you add refrigerant and you still get no subcooling…15 superheat. 17 degree delta T. Was at a call till midnight last night. Txv restriction??

[@Progress24.7]

Does it have a liquid receiver? . If you don't get a subcool and ,you do have one, it's going in there and your overcharging. If not. And it's cooling? Then leave it alone. What is it asking for on the data plate? Subcool or superheat? Superheat seems high. Might be slightly overcharged

[@hectorjr.3359]

I'm still a bit confused as to why your suction pressure and saturation temp read true yet you had high superheat 🤔

[@EdgeTekHVAC]

Hello, Just because the refrigerant pressure gets through the valve does not mean enough liquid refrigerant is being flashed through the valve. With 410A pressures the pressure seems to get through but if the TXV is malfunctioning or is restricted with debris then quantity of liquid required is not flashed through the valve. Feel free to reach out to our technical services team for more clarification.

[@latreshahigh916]

Hi Greg can i get a copy of your job check sheet if possible, Thanks!!!!

[@EdgeTekHVAC]

Can you email me at [e-mail] and I'll send.

[@jamesfields4149]

Do you have a blank copy of that example I could download so I can write my temps on to diagnose my systems......I think you called it a Job check out sheet..........

[@EdgeTekHVAC]

Hi James - we do. What is your email address? I'll send them to you. Thanks, Barb

[@gustavomolina8399]

EdgeTek HVAC Barb can you send one my way too. Please! [e-mail]

[@adamsinwich1942]

I would very much like one too please, [e-mail]

[@jamesfields4149]

[e-mail] Please send me a copy of your job check out sheet you used in this video Thank you for making these video's

[@vacationhome6743]

[e-mail] me too please

[@uncleslappynuts2155]

What gas, 410a guessing

[@aberish]

Can you send me the symptom cards if you have them like a postcard

[@oso1165]

what about how to tell if its overcharged

[@EdgeTekHVAC]

Hello, Low superheat and high subcooling, high head pressure and high suction pressure and High amperage are some of the indicators of a overcharged system.

[@frankhernandez4476]

Would you be able to email me one of those check sheets ?

[@EdgeTekHVAC]

Hi Frank, these sheets can be found through our online literature library here: literature.nortekhvac.com/Unbranded/HVAC/SEARCH/0E43A926-5BF6-2AE6-1C15-733CDF8E2106

[@dswilliamson2112]

You should be a weather forecaster. J/k thanks for the info

[@77777771955]

Talks way too fast. Would not want to be student.

[@enriqueramirez4232]

This guy has no idea what he’s talking about. All he’s doing is reading numbers of a chart. Anybody could do that

[@edfo7068]

What did he get wrong?

[@billbaber6653]

Too fast please