Way back in 1973, at the US Naval school of Air Conditioning and Refrigeration, I was taught that the function of a TXV was “to meter the proper amount of refrigerant according to the heat load, and to maintain superheat. I still taught that to my apprentices until 2019. Your presentations are the best that I have seen in my 45 years in HVAC, both as a field service engineer and apprenticeship instructor. Keep the videos comming
Yes sir, not a HVAC tech person; I did the compressor fan removal wire test for the TXV on my 4-ton Trane system. I took the purple wire off of the run start, common capacitor, rather than the contactor as shown by you in U-tube video. The contactor was more difficult to reach than the purple wire on the capacitor, same result, the fan stopped turning. I watched the low side pressure stat within 5 to 10 psig of the original value while the head pressure went to 300psig. A very smart way to check the TXV, thank you so much for the demonstration! I was not looking forward to taking the plenum apart to get to the air dryer and the TXV bulb to test them. Thank you Sir, regards Joseph
I’m sure compliments on a video that is a few years old will always be appreciated so here is another one. Thank you for making this great video. This helped me a lot while diagnosing my sweating liquid line. I wasn’t sure if it was a txv problem or a restricted liquid drier. This will help eliminate me opening up the txv for no reason. Kudos to you for your knowledge. Thank you!
I, too, have been an instructor in several different fields of technical ability. I appreciate your demeanor and your soft-spoken direction. I aspire to that myself. Thank you for not using a big fingers and elbows two point stuff. Clear minimal pointing perspective are optimal. Thank you very much. Hope to perhaps meet you one day and shake your hand. Best wishes to a consummate professional.
That was great, Eric! Highly informative, well delivered. But am I in trouble??? I'm not a professional HVAC technician. Nor have I ever been to HVAC school. But I do have a manifold gauge set. Couple, actually. And I did take and pass the EPA certification and have a universal rating. Fwiw. But I've been doing my own HVAC since before the certification idea that came about as a result of the govt forced elimination of R22. I hope that lets me participate. 😂 I followed you fully and really appreciated learning this method of checking TXV operation.
Excellent video, I'm electronic tech (voice/data) but not HVAC, now I know what to look for when the HVAC tech shows up. They just replaced TXV on my new ( 6 month) Goodman Heat Pump with a piston.
Wow! Why in the world would they have done that? Sounds like you had zero comissioning on your system at install. Was it done at both the indoor and outdoor units? Also, sounds like you no longer have a valid warranty. There's a reason why the industry is moving away from fixed metering. Swapping out the TXV presents a problem for the next guy who comes to service your unit and rely on the manufacturer's "plate."
Is it possible to have a functioning TXV, ie maintaining superheat, but superheat is high? Check liquid line temp between condenser and evaporator, about 1F difference so no restriction.
Great video, but i had an issue where the walk in freezer coil was not doing a good job cooling the space, superheat at the evap was 39, Suction pressure 17psi, i had to charge the unit to get proper subcool values, how cam i use the information in this video to diagnose a restricted txv? I know this video can indicate if a txv is stuck open but what about an restriction where the txv cant allow much refrigerant through? I already checked across the drier and other places
This video is exclusively meant to test if a TXV is vunctioning on a high - temperature air conditioning system. The techniques mentioned in this video are not able to diagnose a restricted TXV by themselves. A restricted TXV and on that has an improper superheat spring adjustment will behave th esame way. Restrictions are one of the most difficult things to diagnose because other problems will create similar symptoms. While refrigeration systems also have TXVs, they experience a lot more dynamics than an air conditioning system. They are different enough that I consider them to be completely different animals and none of my training is meant to address refrigeration systems.
Great video, if TXV is bad both pressures should up when cond.fan disconnected and if TXV good only head pressure goes up? And suction remain same. Plz do reply , blessing from CA
That's a good one! meanwhile, by the time you have taken those fancy gadgets out of their padded case, and done all the work to dig the sensing bulb out of it's home, and put it back nicely and fixed all the armaflex and cork tape and mastic you had to remove to get to the little bugger, the tech who followed this advice is already paid and on to the next job or at home with their family at a decent hour!
During this test test (ie raising head pressure) if pressure remains the same then TXV is good. What would bad look like. How much change in the suction pressure would be considered bad.
Thank you. I had to take a 32 oz wide mouth filled of ice water and ran back to the condenser to see if the txv was bad. It was. This is a better method. Like a professional instead of asking for a cup of water and running around to the unit.
Brilliant, simply brilliant. 👏 Does blocking the intake or discharge air produce a similar result without removing live wiring and potentially shorting out something, like my lifespan?
A TXV stuck closed will show very low or zero suction pressure with very high head pressure, often to the point of opening the compressor's internal pressure relief valve which will then cause pressures to nearly equalize.
What a jewel! If you were a betting man, you’d win the bet every time that I’ll be using this trick for the rest of my career! Thanks for the _great_ content.
I would think you could do the converse and instead of increasing head pressure by blocking air flow, you can use a garden sprayer filled with ice and water to cool the condenser coils and drop the head pressure to see if the TXV responds to that or not. Right??
Any way you can make a dramatic change to head pressure can test the TXV. I find raising head pressure to be much easier, faster, and more reliable than lowering it. Also, suddenly lowering head pressure can also cause suction pressure to fall by underfeeding the txv and will cause uncertain results and confusion.
No. Switching a Heat pump from heat to cool during a cycle will upset everything for a few minutes until it reaches a new equalibrium. This test should be done when the system is in cooling mode and operating in normal equilibrium and has achieved steady - state operation after running for at least ten minutes.
I do a lot of maintenance calls and if the system is cooling pressures look good. I am not going to open up a can of worms. If that txv is stuck and acting like a piston and there is no problem with cooling. l et it go!
Very good information bro on that TXV so what you saying if your gage did not respond when you stop the fan it clearly saying that your TXV is not working thanks you God bless keep it up
Hi, I maintain over 100 Rheem package units at our resort. The other day, I responded to a call where water was leaking into the ceiling. When I arrived, the evaporator coil and compressor were covered in ice. There is a lot of debate around the shop as to why this happened. Airflow was okay. The coil was clean and after thawing everything out, the blower motor didn’t have any problems pulling the filter panel closed on it’s own. Some of the technicians believe that the doors to the room below were the cause because they were open to the4 hallway, even though the hallway was being cooled by another package unit. The high side gauge was only about 10 degrees above ambient (104 / 115), and the low side gauge was around 42 degrees. I’m accustom to seeing the high side gauge around 30 degrees above ambient. The compressor was pulling 15amps on all three legs and the condenser coil was clean. I moved the TXV bulb outside the unit, and nothing changed with the low side press/temp which made me pause. Adding refrigerant didn't change anything either. There was 6 degrees superheat and almost 0 degrees of sub cooling, but package units are difficult to make accurate measurements because all the components are tucked away in the cabinet. I think something is wrong with the TXV, but I don't know how to make a positive diagnosis with a package unit. The other technicians believe, that the coil can still freeze even with 75 degree air is flowing through it. Any thoughts?
As a DIYer it appears to me that this is a good test and absolutely worth doing but it is testing the valve and balancing spring only. The bulb is not checked as to whether it is responding to temperature change of the suction line as the conditions change for the evaporator coil.
So Eric would it be safe to say that if you have an irregular amp draw that txv could be in the culprit category along with dirty filter slow running fan in or out and some other restriction.
If your TXV was slammed shut, you may have high compressor amp draw, but that would be the least of your problems. The internal pressure relief would probably pop before you got your amp clamp out. Most of the time, any condition that reduces refrigeration capacity (less cooling) will have a slightly lower amp draw including the conditions you mentioned. Difficult to perceive unless you have a "before" measurement to compare to. Remember, compressor amp draw will vary along with cooling load.
Great video! Thank you for sharing your experience and knowledge. When TXV of my AC was warmed up the the suction pressure increased and head pressure went down. In this moment case, Does this proof the txv is not faulty? The problem is 48 F superheat and 20 F subcool and when txv was warned up both supermarket and subcool went down. Thank you in advance for answering my question.
You can also test to make sure the TXV is opening by going the other way - cooling down the liquid line and reducing the liquid line pressure. For example, on a hot day, run water over the condenser coils. It doesn't take much. Even a decent "mist" of water with good coverage over the condenser will do, and may be better as the fan doesn't have to move a large mass of water through the condenser coils. This cools the condenser, which reduces the liquid line pressure (aka "head pressure") . You'll see subcooling drop as the saturation point of the refrigerant in the condenser drops, and it drops at a rate faster than the liquid line temp, thereby reducing subcooling. In effect you are replacing refrigerant subcooling with water evaporation cooling. If the TXV is operating correctly, it will keep open up in response to the reduced high side pressure to maintain superheat - as long as there is enough refrigerant in the system to keep the condenser and evaporator adequately filled on a high load day. MesureQuick will tell you that pretty quickly. Then again, MeasureQuick does not understand the misting process. If the superheat goes up to, say, 25 due to a low refrigerant charge, it may report that the TXV bulb is stuck closed or the bulb lost its charge. By the way, the make mister kits you can mount on condensers. For example, see Cool-N-Save, coolnsave.com/product/cool-n-save-ac-misting-kit/.
Any way to create a fast and dramatic change in head pressure will provide a good test on the txv. Dropping pressure quickly may have the unintended consequence of also dropping suction pressure which can create confusion. If that works for you, that's great. I have seen a garden sprinkler set up as a temporary remedy when a condenser fan fails on a multi-fan commercial RTU plenty of times.
Can i disconnect the brown cable at the capacitor with the power off, and then turn on the unit after securing the fan brown cable so it wouldn't short out, then turn on the unit? Would that work as well, i only have my right arm and don't want to take any chances. Thank you.
Covering the condenser will drive head pressure up and sometimes that works good. Many outdoor units have built in systems that try to prevent this. Carrier units have domed tops. Trane units have a solid top with multiple outlets around the perimeter. I personally find it easier to yank the fan wire since I have a pliers right there and anything I could use to cover the condenser is all the way back at the van.
A TXV that is slammed shut or mostly shut will cause the head pressure to soar and can cause higher amp draw on the compressor. In that case, it won't run very long for you to take a meaurement before the internal pressure relief opens and the amp draw drops very low.
I too enjoyed the video but I didn't get the definitive answer on the TXV being good or bad. I hear "stuck in one spot" bad, but then I hear in the comments "stays in one spot, functioning properly" which is what a TXV is supposed to do, keeping the superheat constant. I'm subscribing because I think you really know your stuff! So in this case, was it good or bad? Thanks
It would be more accurate to say "stuck in one spot, not functioning properly, but still delivering performance that is good enough for the customer to not notice the problem in spite of the fact that it is technically broken". Hope that helps! The TXV in the video is perfectly fine.
While manipulating airflow across the evaporator does have an effect, it is less dramatic than manipulating air flow across the condenser. Also, unless you have wireless gauges that read to your cell phone, it is kind of hard to see your gauges at the outdoor unit while you are at the indoor fan.
Hey man I just saw that video in that case to say that you have a bad txv in that scenario the suction line pressure had to raise up as well? This is a great video man can you tell me in that scenario the txv is doing his job?
I have a 410a unit m trying to figure out . If it the txv or not . Low side is 158 Psig with 17 sh and 288 psig on the high with AC if 1.4 Would the txv be bad thanks
Is it possible that if the TXV is failed closed, the suction pressure side could show basically a vacuum on the gauge set? My service tech showed me his gauge set with the suction side showing zero pressure. He said that either the TXV is closed completely or there is a major obstruction somewhere.
Yes, a TXV stuck fully closed will essentially create a "pump down" where liquid will stack up in the liquid line and condenser and the evaporator and suction line will pull down to a vacuum.
@@hvacservicementor thanks very much for your speedy reply. I am a mechanical engineer so I understand a lot of this and agree with you that this is a job for the pro's. Thanks again.
I've never messed with trying to replace a power head by itself. I feel that trying to rebuild a TXV in the field carrys too much risk. I know there are plenty of refrigeration guys who will disagree. As rare as it is to need to mess with one, it is even rarer to find rebuild parts on the shelf ready to go for AC systems. I always replace the whole thing.
Good eye. I didn't share the refrigerant that was is use because I't doesn't have a bearing on the validity of the test. It works for any refrigerant. This one happens to be R22.
It will either trip a high pressure switch if it has one, the internal bypass valve will open if it has one, or the compressor will overheat and trip it's internal overload switch. If that happens for any extended time it will usually burn it out.
Only bad things... This is why this advice is for qualified techs only. You have to be observant and make sure you don't exceed the high pressure rating on the unit or the high pressure cutout if so equipped.
@@christianruvalcaba7788 yeah u got it. When 410a was introduced i remember first feeling was .. umm not as cold as r22 with in 10 to 20 minutes when compressor kick in... Nowadays i feel it less. Right as u said... system improving... Thx Eric.
@@christianruvalcaba7788 Imagine how good systems could be today with the advances and using R22. Many characteristics of R22 make it a better refrigerant than 410A. There's a white paper out there delineating the differences which came out in the era of switchover.
WRONG hot bulb will open txv to let more refrigerant tru increasing suction pressure cold bulb will shut txv less refrigerant tru equals lower suction pressure
30 years and this is the first time I have seen a TXV tested this way. Very cool !! much easier too.
Way back in 1973, at the US Naval school of Air Conditioning and Refrigeration, I was taught that the function of a TXV was “to meter the proper amount of refrigerant according to the heat load, and to maintain superheat. I still taught that to my apprentices until 2019. Your presentations are the best that I have seen in my 45 years in HVAC, both as a field service engineer and apprenticeship instructor. Keep the videos comming
Wow you’ve been in the field for many years and I’m sure has worked on many different kinds of unit! A lot of experience under ur belt! 👍
Pulling the bulb away is an immediate indicator as to the operational validity of that metering device. Thank you for being well informative.
Yes sir, not a HVAC tech person; I did the compressor fan removal wire test for the TXV on my 4-ton Trane system. I took the purple wire off of the run start, common capacitor, rather than the contactor as shown by you in U-tube video. The contactor was more difficult to reach than the purple wire on the capacitor, same result, the fan stopped turning. I watched the low side pressure stat within 5 to 10 psig of the original value while the head pressure went to 300psig. A very smart way to check the TXV, thank you so much for the demonstration! I was not looking forward to taking the plenum apart to get to the air dryer and the TXV bulb to test them. Thank you Sir, regards Joseph
I’m sure compliments on a video that is a few years old will always be appreciated so here is another one. Thank you for making this great video. This helped me a lot while diagnosing my sweating liquid line. I wasn’t sure if it was a txv problem or a restricted liquid drier. This will help eliminate me opening up the txv for no reason. Kudos to you for your knowledge. Thank you!
Glad you enjoyed it!
I’m a truck driver and I decided to replace my evaporator and condenser myself. I will try this when I get home.
This was a super !!! video. You get to test the TXV without pulling things apart and risking doing damage. Thank you.
But you don't need to test a txv when everything it's ok, if the system is operating good, it's not necessary to do this
That all depends on if the airflow is correct and the line set is correct and there’s no kinks etc..❤
if its bad whats going to happen at the suction pressure? It will go up?
I, too, have been an instructor in several different fields of technical ability. I appreciate your demeanor and your soft-spoken direction. I aspire to that myself. Thank you for not using a big fingers and elbows two point stuff. Clear minimal pointing perspective are optimal. Thank you very much. Hope to perhaps meet you one day and shake your hand. Best wishes to a consummate professional.
Incredible. I never heard of such a test, great info!
nice information. Also, instead of removing the bulb. can you just take a hot/warm towel and put it over the bulb and likewise for a cold check.
Excellent video. Simple way to test a TXV. Thanks a lot for sharing this knowledge!
Thank you for the knowledge, success for "HVAC ......." ... Pekalongan, Central Java, Indonesia attended
You are the man.. so what would I expect to see if I upped the head pressure with a bad txv? I see with a good txv the low side stayed the same
Suction pressure will rise with head pressure because the TXV is unable to control it.
I very rarely write reviews but I decided to write you are truly God in this industry TNX!
Congratulations you are passed . You are the one who understand " the action " in a Refrigration cycle.
That was great, Eric! Highly informative, well delivered. But am I in trouble???
I'm not a professional HVAC technician. Nor have I ever been to HVAC school. But I do have a manifold gauge set. Couple, actually. And I did take and pass the EPA certification and have a universal rating. Fwiw. But I've been doing my own HVAC since before the certification idea that came about as a result of the govt forced elimination of R22. I hope that lets me participate. 😂 I followed you fully and really appreciated learning this method of checking TXV operation.
Great video not trying to over complicate things so only certain mindsets understand would be a great HVAC instructor
Many college professors can't get that when your dropping $100,000 on an education you deserve to learn how to do the job ...
Top notch explanation and with field example 👏
as a new tech here, that shows that the TXV was operating properly, if it was bad would my suction line pressures rise as well or decrease?
If TXV is frozen in some mid position, it will behave like a fixed metering device and suction pressure will rise along side the head pressure.
Excellent video, I'm electronic tech (voice/data) but not HVAC, now I know what to look for when the HVAC tech shows up. They just replaced TXV on my new ( 6 month) Goodman Heat Pump with a piston.
Wow! Why in the world would they have done that? Sounds like you had zero comissioning on your system at install. Was it done at both the indoor and outdoor units? Also, sounds like you no longer have a valid warranty. There's a reason why the industry is moving away from fixed metering.
Swapping out the TXV presents a problem for the next guy who comes to service your unit and rely on the manufacturer's "plate."
Is it possible to have a functioning TXV, ie maintaining superheat, but superheat is high? Check liquid line temp between condenser and evaporator, about 1F difference so no restriction.
Great video, but i had an issue where the walk in freezer coil was not doing a good job cooling the space, superheat at the evap was 39, Suction pressure 17psi, i had to charge the unit to get proper subcool values, how cam i use the information in this video to diagnose a restricted txv? I know this video can indicate if a txv is stuck open but what about an restriction where the txv cant allow much refrigerant through? I already checked across the drier and other places
This video is exclusively meant to test if a TXV is vunctioning on a high - temperature air conditioning system. The techniques mentioned in this video are not able to diagnose a restricted TXV by themselves. A restricted TXV and on that has an improper superheat spring adjustment will behave th esame way. Restrictions are one of the most difficult things to diagnose because other problems will create similar symptoms. While refrigeration systems also have TXVs, they experience a lot more dynamics than an air conditioning system. They are different enough that I consider them to be completely different animals and none of my training is meant to address refrigeration systems.
Great video, if TXV is bad both pressures should up when cond.fan disconnected and if TXV good only head pressure goes up? And suction remain same. Plz do reply , blessing from CA
"You can't watch the sensing bulb and the suction pressure at the same time."
*Job Link probes have entered the chat*
That's a good one! meanwhile, by the time you have taken those fancy gadgets out of their padded case, and done all the work to dig the sensing bulb out of it's home, and put it back nicely and fixed all the armaflex and cork tape and mastic you had to remove to get to the little bugger, the tech who followed this advice is already paid and on to the next job or at home with their family at a decent hour!
@@hvacservicementor oh fuck, burn XD
@1:54, I've had the 1968 edition since the late '70s.
Unplug condenser fan and watch suction pressure, it should have little or no change if the TXV is metering correctly.
Thanks you so much coming from a new tech.
You bet!
During this test test (ie raising head pressure) if pressure remains the same then TXV is good. What would bad look like. How much change in the suction pressure would be considered bad.
Very well explained, thank you sir.
Thank you. I had to take a 32 oz wide mouth filled of ice water and ran back to the condenser to see if the txv was bad. It was. This is a better method. Like a professional instead of asking for a cup of water and running around to the unit.
Brilliant, simply brilliant. 👏
Does blocking the intake or discharge air produce a similar result without removing live wiring and potentially shorting out something, like my lifespan?
Yes it does, but the effect is not quite as dramatic depending on how effectively you can block the air flow.
Excellent. There are plenty of HVAC videos that don't use this test.
This is the best explanation ever, 👏 thank you very much
You're very welcome!
Would the results looked similar if the txv is stucked closed? Great video. Thanks
A TXV stuck closed will show very low or zero suction pressure with very high head pressure, often to the point of opening the compressor's internal pressure relief valve which will then cause pressures to nearly equalize.
What a jewel! If you were a betting man, you’d win the bet every time that I’ll be using this trick for the rest of my career! Thanks for the _great_ content.
Thanks, Gary!
I would think you could do the converse and instead of increasing head pressure by blocking air flow, you can use a garden sprayer filled with ice and water to cool the condenser coils and drop the head pressure to see if the TXV responds to that or not. Right??
Any way you can make a dramatic change to head pressure can test the TXV. I find raising head pressure to be much easier, faster, and more reliable than lowering it. Also, suddenly lowering head pressure can also cause suction pressure to fall by underfeeding the txv and will cause uncertain results and confusion.
Very good video, thanks very much
So if I’m testing a TXV on a geothermal heat pump, I can switch to heat to effectively do this same test?
No. Switching a Heat pump from heat to cool during a cycle will upset everything for a few minutes until it reaches a new equalibrium. This test should be done when the system is in cooling mode and operating in normal equilibrium and has achieved steady - state operation after running for at least ten minutes.
This is a informative video that will help me a lot,related to my job .thank you so much for sharing your knowledge 🙌
I do a lot of maintenance calls and if the system is cooling pressures look good. I am not going to open up a can of worms. If that txv is stuck and acting like a piston and there is no problem with cooling. l
et it go!
The compressor will go into thermal overload???
Very good information bro on that TXV so what you saying if your gage did not respond when you stop the fan it clearly saying that your TXV is not working thanks you God bless keep it up
Hi, I maintain over 100 Rheem package units at our resort. The other day, I responded to a call where water was leaking into the ceiling. When I arrived, the evaporator coil and compressor were covered in ice.
There is a lot of debate around the shop as to why this happened. Airflow was okay. The coil was clean and after thawing everything out, the blower motor didn’t have any problems pulling the filter panel closed on it’s own.
Some of the technicians believe that the doors to the room below were the cause because they were open to the4 hallway, even though the hallway was being cooled by another package unit.
The high side gauge was only about 10 degrees above ambient (104 / 115), and the low side gauge was around 42 degrees. I’m accustom to seeing the high side gauge around 30 degrees above ambient. The compressor was pulling 15amps on all three legs and the condenser coil was clean.
I moved the TXV bulb outside the unit, and nothing changed with the low side press/temp which made me pause. Adding refrigerant didn't change anything either. There was 6 degrees superheat and almost 0 degrees of sub cooling, but package units are difficult to make accurate measurements because all the components are tucked away in the cabinet.
I think something is wrong with the TXV, but I don't know how to make a positive diagnosis with a package unit. The other technicians believe, that the coil can still freeze even with 75 degree air is flowing through it. Any thoughts?
What are the temperatures on the filter dryer? Did you nail the problem?
As a DIYer it appears to me that this is a good test and absolutely worth doing but it is testing the valve and balancing spring only. The bulb is not checked as to whether it is responding to temperature change of the suction line as the conditions change for the evaporator coil.
Keep it up!
(11:25) Either that's an R-22 unit, or that evaporator coil was freezing.
Love your videos.
Yes. R-22.
So Eric would it be safe to say that if you have an irregular amp draw that txv could be in the culprit category along with dirty filter slow running fan in or out and some other restriction.
If your TXV was slammed shut, you may have high compressor amp draw, but that would be the least of your problems. The internal pressure relief would probably pop before you got your amp clamp out. Most of the time, any condition that reduces refrigeration capacity (less cooling) will have a slightly lower amp draw including the conditions you mentioned. Difficult to perceive unless you have a "before" measurement to compare to. Remember, compressor amp draw will vary along with cooling load.
@@hvacservicementor thaNks for the insight..
That's a really good test and explanation. Thanks for sharing.
Hi , can you show us troubleshooting with Piston? Thank you.
Great video! Thank you for sharing your experience and knowledge. When TXV of my AC was warmed up the the suction pressure increased and head pressure went down. In this moment case, Does this proof the txv is not faulty? The problem is 48 F superheat and 20 F subcool and when txv was warned up both supermarket and subcool went down. Thank you in advance for answering my question.
I think if you have to force the TXV open no matter where you put it , it's a bad TXV, it's unable to work by itself
You can also test to make sure the TXV is opening by going the other way - cooling down the liquid line and reducing the liquid line pressure. For example, on a hot day, run water over the condenser coils. It doesn't take much. Even a decent "mist" of water with good coverage over the condenser will do, and may be better as the fan doesn't have to move a large mass of water through the condenser coils. This cools the condenser, which reduces the liquid line pressure (aka "head pressure") . You'll see subcooling drop as the saturation point of the refrigerant in the condenser drops, and it drops at a rate faster than the liquid line temp, thereby reducing subcooling. In effect you are replacing refrigerant subcooling with water evaporation cooling. If the TXV is operating correctly, it will keep open up in response to the reduced high side pressure to maintain superheat - as long as there is enough refrigerant in the system to keep the condenser and evaporator adequately filled on a high load day. MesureQuick will tell you that pretty quickly. Then again, MeasureQuick does not understand the misting process. If the superheat goes up to, say, 25 due to a low refrigerant charge, it may report that the TXV bulb is stuck closed or the bulb lost its charge. By the way, the make mister kits you can mount on condensers. For example, see Cool-N-Save, coolnsave.com/product/cool-n-save-ac-misting-kit/.
Any way to create a fast and dramatic change in head pressure will provide a good test on the txv. Dropping pressure quickly may have the unintended consequence of also dropping suction pressure which can create confusion. If that works for you, that's great. I have seen a garden sprinkler set up as a temporary remedy when a condenser fan fails on a multi-fan commercial RTU plenty of times.
So this is mean ser that the txv. Was working very good..thanks
Can i disconnect the brown cable at the capacitor with the power off, and then turn on the unit after securing the fan brown cable so it wouldn't short out, then turn on the unit? Would that work as well, i only have my right arm and don't want to take any chances. Thank you.
If there are multiple evaporators connected with one single compressor, how do we check each of the txv's.
That is very tough. Very nearly impossible.
What if I buy a replacement TXV, that was R12, and now the only available is 134? My system is still R12… will the value of superheat be incorrect?
Would it do the same job if i cover the condenser? Head pressure will go up. Thank you.
Covering the condenser will drive head pressure up and sometimes that works good. Many outdoor units have built in systems that try to prevent this. Carrier units have domed tops. Trane units have a solid top with multiple outlets around the perimeter. I personally find it easier to yank the fan wire since I have a pliers right there and anything I could use to cover the condenser is all the way back at the van.
Great Video Joe H Navy Seabee
will a bad txv cause over amping?
A TXV that is slammed shut or mostly shut will cause the head pressure to soar and can cause higher amp draw on the compressor. In that case, it won't run very long for you to take a meaurement before the internal pressure relief opens and the amp draw drops very low.
I too enjoyed the video but I didn't get the definitive answer on the TXV being good or bad. I hear "stuck in one spot" bad, but then I hear in the comments "stays in one spot, functioning properly" which is what a TXV is supposed to do, keeping the superheat constant. I'm subscribing because I think you really know your stuff! So in this case, was it good or bad? Thanks
It would be more accurate to say "stuck in one spot, not functioning properly, but still delivering performance that is good enough for the customer to not notice the problem in spite of the fact that it is technically broken". Hope that helps! The TXV in the video is perfectly fine.
In this case the txv valve was good or bad?
It was good.
Also, where do you actually find cold iced water or hot water?
i thought you're going to manipulate the indoor fan, is it the same?
While manipulating airflow across the evaporator does have an effect, it is less dramatic than manipulating air flow across the condenser. Also, unless you have wireless gauges that read to your cell phone, it is kind of hard to see your gauges at the outdoor unit while you are at the indoor fan.
Hey man I just saw that video in that case to say that you have a bad txv in that scenario the suction line pressure had to raise up as well? This is a great video man can you tell me in that scenario the txv is doing his job?
I have a 410a unit m trying to figure out . If it the txv or not . Low side is 158 Psig with 17 sh and 288 psig on the high with AC if 1.4
Would the txv be bad thanks
Is the procedure the same for heating with a heat pump?
In cooling mode, yes. I wouldn't bother with it in heating mode.
Did you off somthing to test the low side guage...ser.
thank you for this video been looking for a good way to test
Please explain the head pressure about other refrigerant. (I believe head pressure situation r 22 explain ) Thanks
Great video love it, I was trying to long in to your website but it was not letting me
site was in transition go to hvactraining.squarespace.com/
Suction pressure Shouldn’t go more than how much psig from were it was sitting at?
Great lesson dear,.,.,. easy to follow explanation
Thanks
That is an easy way to test it.
Wow! Great method, and great presentation!
This is a great video. Thank you. This will help me a lot.
Can this work on a Commercial Refrigeration Systems, Racks and Ice Machines too?
This is a great video. Thank you so much.
Excellent Demo. TY
whats the indoor and outside temperature. Assuming this is operating in cool mode. Not heat mode.
👍💪🇺🇸❄️ Great information. ? Would this work on a walkin box with a pumpdown system with a liquid receiver n solenoid valve ?
pretty neat trick learned something today thanks!
Thanks very informative. Is this also applicable to a watercooled condenser?
yes you close the water valve
Thanks for your help.
Is it possible that if the TXV is failed closed, the suction pressure side could show basically a vacuum on the gauge set? My service tech showed me his gauge set with the suction side showing zero pressure. He said that either the TXV is closed completely or there is a major obstruction somewhere.
Yes, a TXV stuck fully closed will essentially create a "pump down" where liquid will stack up in the liquid line and condenser and the evaporator and suction line will pull down to a vacuum.
@@hvacservicementor thanks very much for your speedy reply. I am a mechanical engineer so I understand a lot of this and agree with you that this is a job for the pro's. Thanks again.
Great video great instructor.
do you have to recover the refrigerant to replace a TXV power head?
I've never messed with trying to replace a power head by itself. I feel that trying to rebuild a TXV in the field carrys too much risk. I know there are plenty of refrigeration guys who will disagree. As rare as it is to need to mess with one, it is even rarer to find rebuild parts on the shelf ready to go for AC systems. I always replace the whole thing.
That's simply great, I only feel bad, that I never thought about that before.
Thank you❤
Good stuff. Thanks for sharing!
What if it is a walk in freezer and it has a headmaster control?
Try it and see. let me know.
How does this help me if the txv pin is stuck or stuck closed
low pressure will rise with head pressure if txv is stuck txv not able to maintain proper super heat
But why was your saturation temp so low? About 15 degrees assuming this unit uses 410a that’s well below freezing 🥶
Good eye. I didn't share the refrigerant that was is use because I't doesn't have a bearing on the validity of the test. It works for any refrigerant. This one happens to be R22.
Wow. That is a great tip! Thanks!
Bro! Excellent! Great video! You have made my life easier!
What happens if u let the head pressure keep rising
It will either trip a high pressure switch if it has one, the internal bypass valve will open if it has one, or the compressor will overheat and trip it's internal overload switch. If that happens for any extended time it will usually burn it out.
Only bad things... This is why this advice is for qualified techs only. You have to be observant and make sure you don't exceed the high pressure rating on the unit or the high pressure cutout if so equipped.
I'm figuring that was an r22 system
Couldn't you just spray water over the condenser as well?
Usually for me that's when the spade pulls off
Hey Eric how u doin.. i was searching for the video you've made on wich is better r22 or 410a but i couldn't find it...
I haven't made a video like that. I don't consider one better than the other. They're just different.
@@hvacservicementor thx for the answer and sorry my bad it might be on another channel get confused with you coz i follow lots of ur video 🙏🙏
@@fuyftuy back when they just made R410A, R22 was better. But as technology advances they've become more or less equal.
@@christianruvalcaba7788 yeah u got it. When 410a was introduced i remember first feeling was .. umm not as cold as r22 with in 10 to 20 minutes when compressor kick in...
Nowadays i feel it less. Right as u said... system improving...
Thx Eric.
@@christianruvalcaba7788
Imagine how good systems could be today with the advances and using R22. Many characteristics of R22 make it a better refrigerant than 410A. There's a white paper out there delineating the differences which came out in the era of switchover.
When testing a TXV isn't the pressure supposed to go up when sensing bulb is in cold water and go down when in hot water???
WRONG hot bulb will open txv to let more refrigerant tru increasing suction pressure cold bulb will shut txv less refrigerant tru equals lower suction pressure
How can I get your book?