Tool List- www.amazon.com/shop/acservicetech Support- www.patreon.com/acservicetech For those that are looking for the tools used in the videos: (Linked Below) Here is the Link for the Yellow Jacket Refrigerant Manifold Gauge Set used in the videos- amzn.to/2aenwTq Here is a link to Refrigerant hoses with valves used in the videos- amzn.to/2aBumVI Here is a link to the UEI DL389 Multimeter used in the videos- amzn.to/2av8s3q Here is a link to the Hilmor 4 port Aluminum Manifold Gauge Set- amzn.to/2m4QLik Here is a link to the Digital Refrigerant Scale used in the videos- amzn.to/2b9oXYl Other tool links can be found in the video description section. ACSERVICETECH is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.
4:37... to have a good thermal contact get some copper tape, or copper foil, wrap around the bulb and the tube a few times (so both are inside that foil "envelope"), and use as you say, a hose clamp or two, and then some insulation stuff around (btw...even alum. foil could do, but copper is the best 'cause it conducts heat much better).
TXVs should be down stream from the evaporator coils about 6-10 inches and It should be at 2pm if your going straight. Great video thanks for some information there.
Hey Harry, the txv is installed upstream of the evaporator coil and right before the distributor tubes. The length away from the coil would depend if you have distributor tubes or not. The bulb position would depend on the diameter of the suction tube. These were just general rules for smaller residential systems, thanks Harry!
Nice Video's all around. Question, in the electronic industry we use a thermal paste to insure good heat transfer. Has the HVAC industry tried thermal paste with the TXV bulb installation? I am not in the HVAC industry, but just a homeowner trying to educate myself on how residential system work.
It's no necessary, the txv exist before the pyramids were built and they're still doing its job very well, do you think a car needs 5 wheels to run better?
Some package unit ports are placed in the correct spots for checking superheat and subcooling. If they are not then you should look for a manufacturer charging guideline which will say where to read pressure and temp. I know this video is on a split system but the same thought process would apply if the ports were not in the right location and you were trying to find where the sat state temp could be taken from- th-cam.com/video/MHth2vH3np4/w-d-xo.html
@@acservicetechchannel Good video, I would like to ask you a question, my a/c not blowing cold, it's a 2 year old rheem unit. My head pressure is 148 and my suction pressure is 248 my temperature from the plenum is 64 degree, I recovered the freeon and vacuum it and added new freeon, what possibly can I do next?
Does it matter which way the tube needs to be facing as in direction ? On horizontal could you flip it around and have it facing the opposite direction ?
I want to thank you for all of your videos, I have learned a lot from you But I have a question for you when installing a system with a txv is it a good idea to remove the txv bulb from the succión line when welding the set line to the a coil?
Yes absolutely, i always do that! In the HVAC Brazing Playlist here there is a three part video on it, thanks!- th-cam.com/video/5V_da4ymlvM/w-d-xo.html
do you have anything on a hunting txv, worked on a 4 ton 14seer amana the other day with an oem non adjustable txv, the valve is hunting sh 5f-10f and sc 6f-8F, manufacturer recommends 7-9F for sh and sc, the airflow is with in a range, bulb is set on 3 oclock after the equalizer, should i try moving it upstream and on 4 oclock, bump a fan bit more any suggestions? thanks
Thanks for the question! What were the actual pressures, what was the actual superheat temp ranging, and did you just add refrigerant in? You said the valve was hunting 5f-10f. Does that mean the actual superheat was 5f-10f or was it 20f ranging 5f-10f? Thanks
Read this article online. Lot's of good stuff! "Tips For Preventing Superheat Hunting In TXVs" www.achrnews.com/articles/83228-tips-for-preventing-superheat-hunting-in-txvs
So some manufacturers wrap it in the coil box and some do not. I recommend putting on two layers of foam tape to be safe when it is in the box in order to sense the correct temp. Thanks for the Comment!
So I have a question, I was troubleshooting a new unit 410A, it was slightly undercharged so I went ahead and charged it up but the low side didn't seemed to increase the pressure at all I added about 1 1/2 lbs and not even a single psi, but the high side kept increasing, is this a txv sensing bulb? Problem
If you are charging and the subcooling keeps increasing but you cannot get the pressure up it is likely the txv. If both are not going up then it is likely airflow. Check out this TXV troubleshooting playlist to confirm this. You can put the sensing bulb in hot water to test the opening of the txv.th-cam.com/play/PLxnHR5_D2ojy2EYzy0YIJkce9sFIQj4-j.html
Since it is spring and pressure driven, it should work but is not advised. They are factory installed horizontal in may instances such as multipoise evap coils. How old was the unit?
OK, I'm at a loss here and I could really use some advice. When my compressor kicks on my high reads roughly 420psi but my low reads around 110 and then begins to drop all the way to zero yet the high side climbs maybe a few psi. If there was a blockage anywhere after the high side test port I would assume the high side would climb as the low side drops. What causes low to drop to zero but high to only climb a few psi? Any advice is greatly appreciated
So when the low side lowers then the high side will actually stay the same or lower itself some while your subcooling increases some. I am assuming we are talking about R-410A refrigerant. Have you checked out the troubleshooting txv videos playlist on the channel? I show how to test the txv bulb and what the pressures are like when putting the bulb in hot or ice water. It sounds like a blockage or bad txv but the more details the better. Thanks for the question!
+acservicetech It is a 3.5 ton, outdoor compressor, attic air handler. I used your video to diagnose and determine that the TXV was bad. I had the TXV replaced about three weeks ago and it was working beautifully. Just a couple days ago it quit cooling and the compressor sounded like it was pulling a vacuum on the suction side so I shut it down and connected my gauges. Upon posting the unit back up the suction and liquid line pressures were right on the mark but the suction line was around 80 degrees F and the air inside was slightly cool. After running for roughly 20 minutes the liquid line pressure increased slightly to around 440psi and the low dropped all the way to zero so I shut the unit down again. Today I tried to pull the freon into the compressor to flush the system and install a new filter but I could only get the suction pressure down to around 40psi before the compressor kicked off. I'm at a complete loss here. I figured if there was a blockage on the liquid side the head pressure would have sky rocketed but the pressures read perfect yet I get no cool air and the suction line gets only slightly cooler than ambient temperature.
Did you check the screen in the liquid line near the txv to see if it was clogged? Is there a great temp difference from one side of the filter drier to the other side? Is the outdoor unit a heat pump or condenser? In the text you wrote outdoor compressor. Some units that I try to pump down are just not strong enough to do it so I have to close the service valves and recover the refrigerant. You said the suction and liquid pressures were right on the mark but the suction line was 80 degrees. This means you have too much superheat from what I can tell from your post. If that is the case then yeah there is a restriction of some sort before the evap. Did you try taking the bulb off of this new txv and putting it in hot water again to see if the superheat goes down and the valve opens fully. If it does open fully then there must be some issue with this new txv, if not it is an intermittent problem like you said maybe being the filter dryer blocking or a particulate from the filter drier breaking loose. Even though it would seem strange to be, try testing the bulb again on this new one first. Did you check out the bulb positioning video that I just posted a few days ago? I hope this helps! Thanks and let me know what you find.
+acservicetech It is a heat pump system. I switched to heat for a few minutes to see if maybe it would dislodge the blockage and possibly trap it in the filter drier and the heat works very well, almost too well as the suction line gets hot enough to melt the foam insulation. I will check everything you said to check and I'll double check my TXV bulb position and test it with the hot water and document my readings. I really appreciate your help and patience, you are a great person for helping others like you do. If I can help in any way, please let me know. I'm a certified automotive tech on the civilian side and a computer tech for the military and am currently going to school for electromechanical engineering but home A/C is one field I lack experience with.
Great video!!! I absolutely agree that 2-3-4-5 o’clock bulb’s position on the suction line makes no difference. I did experiments with 2-4-4-5 o’clock sensing bulb placements and there was no difference in suction line pressure/temperature or SuperHeat value on wall-in coolers or walk-in freezers. I didn’t play with A/Cs yet. For the refrigeration equipment I had R- 404A and R-407A.
Won't the steel straps in contact with the copper tubing create a bimetallic corrosion that could eventually compromise the integrity of both components? For example: a galvanic corrosion through an electrochemical process corrodes the steel strap and piping, causing both to fail. It seems like you'd want to instead use either copper or plastic straps.
These are stainless steel so they don't react with copper due to their properties. If it was a galvanized strap, it certainly would corrode. I would not use any plastic strap or cable tie because of stretching over time and not as strong. Actually some manufacturers provide a type of stainless steel clamp for this with a single screw and nut. Thanks Adam!
Use thermal paste First cover it with electric tape Then armaflex so u can change it later easily . Only using arma flax sticks it all over and u need to clean hard for changing later
Great in-depth question. There are 2-3 schools of thought on that and one is that the txv is there to maintain a good system capacity. The other thought is to maintain a proper superheat for the compressor's sake. Some would say that you need the bulb to read the suction temp after the last device is installed which would affect superheat to make sure that superheat is not lost before reaching the compressor. Some would say that it is more important to fill the evap with the sat state as much as possible and that the compressor may be able to handle a small amount of sat state every once and a while. Others say there really is not much of a change in temp read on the bulb right before or right after the external equalizer. We also use txv's without the external equalization port which is worse for guaranteeing compressor safety. Thanks a lot Randall and awesome question!
i wanted to see what you thought about putting the bulb before or after equilizer. i saw another tech video that said he had a problem with bulb after equilizer due to extra refrigerant from equilizer discharge affecting bulb temp. like a feedback loop that caused the coil to freeze up. seems like there shouldnt be enough liquid coming out of equilizer to affect the bulb sense???? might be wrong. thanks for reply
It would have to leak between the pin and the brass housing inside the txv, highly unlikely that it would be a significant amount. I see manufacturers for ac evaps factory installing external equalizer tube upstream of the bulb and also the way that techs try to install when given the opportunity which is bulb upstream of the tube but it is not like a freeflowing loop inside though, thanks Randall!
Why does TXV manufacturer not produce sensing bulbs with certain sized grooves/curves that can fit on certain sized pipes? Say sensing bulb fit 5/8. 3/4, 1, 1-1/2, etc.
Some manufacturers of evap coils that have the txv preinstalled press a groove into the suction line so the bulb has more sensing surface area, thanks!
So while researching a problem today I came upon a thread that contained a statement by a person mentioning that you should always mount the bulb UPSTREAM of the equalizing tube, so about 12" to the left of where you're showing here or next to that bottom bend although I understand that it's probably not the point of this video. The discharge of the equalizing tube can cause improper metering.
Great in-depth question. There are 2-3 schools of thought on that and one is that the txv is there to maintain a good system capacity. The other thought is to maintain a proper superheat for the compressor's sake. Some would say that you need the bulb to read the suction temp after the last device is installed which would affect superheat to make sure that superheat is not lost before reaching the compressor. Some would say that it is more important to fill the evap with the sat state as much as possible and that the compressor may be able to handle a small amount of sat state every once and a while. Others say there really is not much of a change in temp read on the bulb right before or right after the external equalizer. We also use txv's without the external equalization port which is worse for guaranteeing compressor safety. Thanks a lot Tie Dye and awesome question!
Tool List- www.amazon.com/shop/acservicetech
Support- www.patreon.com/acservicetech
For those that are looking for the tools used in the videos: (Linked Below)
Here is the Link for the Yellow Jacket Refrigerant Manifold Gauge Set used in the videos-
amzn.to/2aenwTq
Here is a link to Refrigerant hoses with valves used in the videos- amzn.to/2aBumVI
Here is a link to the UEI DL389 Multimeter used in the videos- amzn.to/2av8s3q
Here is a link to the Hilmor 4 port Aluminum Manifold Gauge Set-
amzn.to/2m4QLik
Here is a link to the Digital Refrigerant Scale used in the videos-
amzn.to/2b9oXYl
Other tool links can be found in the video description section.
ACSERVICETECH is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.
the best instructional explanation of bulb placement I have seen on TH-cam, many thanks
Thanks Ty!
Thanks again! please keep sharing your experience and tips on field .
Ok, will do!
4:37... to have a good thermal contact get some copper tape, or copper foil, wrap around the bulb and the tube a few times (so both are inside that foil "envelope"), and use as you say, a hose clamp or two, and then some insulation stuff around (btw...even alum. foil could do, but copper is the best 'cause it conducts heat much better).
CPU thermal paste would even be better
I have always used a heat transfer enhancement compound at this joint. Helps with corrosion control also.
Like?
Thank you so much for the best explainion it work very good with me...👍
Glad to hear that
Can the equalization port be installed on the outside right where the pipe exits the housing, when the pipe section inside is very short?
TXVs should be down stream from the evaporator coils about 6-10 inches and It should be at 2pm if your going straight. Great video thanks for some information there.
Hey Harry, the txv is installed upstream of the evaporator coil and right before the distributor tubes. The length away from the coil would depend if you have distributor tubes or not. The bulb position would depend on the diameter of the suction tube. These were just general rules for smaller residential systems, thanks Harry!
thanks for the info, keep the vids comming.
Thank you, will do!
Nice Video's all around. Question, in the electronic industry we use a thermal paste to insure good heat transfer. Has the HVAC industry tried thermal paste with the TXV bulb installation? I am not in the HVAC industry, but just a homeowner trying to educate myself on how residential system work.
It's no necessary, the txv exist before the pyramids were built and they're still doing its job very well, do you think a car needs 5 wheels to run better?
Cool explanation!!!! Very professional. Thank you
Thanks Tapch MC!
On a package unit where do you place your temp probe to check superheat and subcooling?
Some package unit ports are placed in the correct spots for checking superheat and subcooling. If they are not then you should look for a manufacturer charging guideline which will say where to read pressure and temp. I know this video is on a split system but the same thought process would apply if the ports were not in the right location and you were trying to find where the sat state temp could be taken from- th-cam.com/video/MHth2vH3np4/w-d-xo.html
Thanks for the info, good video.
Thanks Ronnie!
@@acservicetechchannel
Good video, I would like to ask you a question, my a/c not blowing cold, it's a 2 year old rheem unit. My head pressure is 148 and my suction pressure is 248 my temperature from the plenum is 64 degree, I recovered the freeon and vacuum it and added new freeon, what possibly can I do next?
Could we move the bulb from inside of the air handler to the outside on to the copper line?
Great video! Few questions if I may
Is it better to mount the bulb outside of the ductwork or inside?
Thank you
I have the same question.
How fragile is the tiny copper line attached to the sensor? home much bending and repositioning can it take before it just snaps?
very nice thank you for sharing!!!
Thanks for your comment!
Does it matter which way the tube needs to be facing as in direction ? On horizontal could you flip it around and have it facing the opposite direction ?
Great video!
Thank you
I want to thank you for all of your videos, I have learned a lot from you
But I have a question for you when installing a system with a txv is it a good idea to remove the txv bulb from the succión line when welding the set line to the a coil?
Yes absolutely, i always do that! In the HVAC Brazing Playlist here there is a three part video on it, thanks!- th-cam.com/video/5V_da4ymlvM/w-d-xo.html
Can it be inside of the evaporator box?
do you have anything on a hunting txv,
worked on a 4 ton 14seer amana the other day with an oem non adjustable txv, the valve is hunting sh 5f-10f and sc 6f-8F, manufacturer recommends 7-9F for sh and sc, the airflow is with in a range, bulb is set on 3 oclock after the equalizer, should i try moving it upstream and on 4 oclock, bump a fan bit more any suggestions? thanks
Thanks for the question! What were the actual pressures, what was the actual superheat temp ranging, and did you just add refrigerant in? You said the valve was hunting 5f-10f. Does that mean the actual superheat was 5f-10f or was it 20f ranging 5f-10f? Thanks
Read this article online.
Lot's of good stuff!
"Tips For Preventing Superheat Hunting In TXVs"
www.achrnews.com/articles/83228-tips-for-preventing-superheat-hunting-in-txvs
Thank you !
if the txv is located inside the coil box do you still want to wrapped with insulation?
or only if is mounted outside of coil box.?
Thanks for sharing
So some manufacturers wrap it in the coil box and some do not. I recommend putting on two layers of foam tape to be safe when it is in the box in order to sense the correct temp. Thanks for the Comment!
So I have a question, I was troubleshooting a new unit 410A, it was slightly undercharged so I went ahead and charged it up but the low side didn't seemed to increase the pressure at all I added about 1 1/2 lbs and not even a single psi, but the high side kept increasing, is this a txv sensing bulb? Problem
If you are charging and the subcooling keeps increasing but you cannot get the pressure up it is likely the txv. If both are not going up then it is likely airflow. Check out this TXV troubleshooting playlist to confirm this. You can put the sensing bulb in hot water to test the opening of the txv.th-cam.com/play/PLxnHR5_D2ojy2EYzy0YIJkce9sFIQj4-j.html
I've seen the TXV itself (not the bulb) installed upside down. Does this cause hangups for the TXV?
Since it is spring and pressure driven, it should work but is not advised. They are factory installed horizontal in may instances such as multipoise evap coils. How old was the unit?
It makes no difference.
OK, I'm at a loss here and I could really use some advice.
When my compressor kicks on my high reads roughly 420psi but my low reads around 110 and then begins to drop all the way to zero yet the high side climbs maybe a few psi. If there was a blockage anywhere after the high side test port I would assume the high side would climb as the low side drops. What causes low to drop to zero but high to only climb a few psi? Any advice is greatly appreciated
So when the low side lowers then the high side will actually stay the same or lower itself some while your subcooling increases some. I am assuming we are talking about R-410A refrigerant. Have you checked out the troubleshooting txv videos playlist on the channel? I show how to test the txv bulb and what the pressures are like when putting the bulb in hot or ice water. It sounds like a blockage or bad txv but the more details the better. Thanks for the question!
+acservicetech
It is a 3.5 ton, outdoor compressor, attic air handler. I used your video to diagnose and determine that the TXV was bad. I had the TXV replaced about three weeks ago and it was working beautifully. Just a couple days ago it quit cooling and the compressor sounded like it was pulling a vacuum on the suction side so I shut it down and connected my gauges. Upon posting the unit back up the suction and liquid line pressures were right on the mark but the suction line was around 80 degrees F and the air inside was slightly cool. After running for roughly 20 minutes the liquid line pressure increased slightly to around 440psi and the low dropped all the way to zero so I shut the unit down again. Today I tried to pull the freon into the compressor to flush the system and install a new filter but I could only get the suction pressure down to around 40psi before the compressor kicked off. I'm at a complete loss here. I figured if there was a blockage on the liquid side the head pressure would have sky rocketed but the pressures read perfect yet I get no cool air and the suction line gets only slightly cooler than ambient temperature.
Did you check the screen in the liquid line near the txv to see if it was clogged? Is there a great temp difference from one side of the filter drier to the other side? Is the outdoor unit a heat pump or condenser? In the text you wrote outdoor compressor. Some units that I try to pump down are just not strong enough to do it so I have to close the service valves and recover the refrigerant. You said the suction and liquid pressures were right on the mark but the suction line was 80 degrees. This means you have too much superheat from what I can tell from your post. If that is the case then yeah there is a restriction of some sort before the evap. Did you try taking the bulb off of this new txv and putting it in hot water again to see if the superheat goes down and the valve opens fully. If it does open fully then there must be some issue with this new txv, if not it is an intermittent problem like you said maybe being the filter dryer blocking or a particulate from the filter drier breaking loose. Even though it would seem strange to be, try testing the bulb again on this new one first. Did you check out the bulb positioning video that I just posted a few days ago? I hope this helps! Thanks and let me know what you find.
+acservicetech It is a heat pump system. I switched to heat for a few minutes to see if maybe it would dislodge the blockage and possibly trap it in the filter drier and the heat works very well, almost too well as the suction line gets hot enough to melt the foam insulation. I will check everything you said to check and I'll double check my TXV bulb position and test it with the hot water and document my readings. I really appreciate your help and patience, you are a great person for helping others like you do. If I can help in any way, please let me know. I'm a certified automotive tech on the civilian side and a computer tech for the military and am currently going to school for electromechanical engineering but home A/C is one field I lack experience with.
Great video!!! I absolutely agree that 2-3-4-5 o’clock bulb’s position on the suction line makes no difference. I did experiments with 2-4-4-5 o’clock sensing bulb placements and there was no difference in suction line pressure/temperature or SuperHeat value on wall-in coolers or walk-in freezers. I didn’t play with A/Cs yet. For the refrigeration equipment I had R- 404A and R-407A.
Won't the steel straps in contact with the copper tubing create a bimetallic corrosion that could eventually compromise the integrity of both components? For example: a galvanic corrosion through an electrochemical process corrodes the steel strap and piping, causing both to fail. It seems like you'd want to instead use either copper or plastic straps.
These are stainless steel so they don't react with copper due to their properties. If it was a galvanized strap, it certainly would corrode. I would not use any plastic strap or cable tie because of stretching over time and not as strong. Actually some manufacturers provide a type of stainless steel clamp for this with a single screw and nut. Thanks Adam!
Use thermal paste
First cover it with electric tape
Then armaflex so u can change it later easily . Only using arma flax sticks it all over and u need to clean hard for changing later
does it matter where the bulb is in relation to external equilizer tap?
Great in-depth question. There are 2-3 schools of thought on that and one is that the txv is there to maintain a good system capacity. The other thought is to maintain a proper superheat for the compressor's sake. Some would say that you need the bulb to read the suction temp after the last device is installed which would affect superheat to make sure that superheat is not lost before reaching the compressor. Some would say that it is more important to fill the evap with the sat state as much as possible and that the compressor may be able to handle a small amount of sat state every once and a while. Others say there really is not much of a change in temp read on the bulb right before or right after the external equalizer. We also use txv's without the external equalization port which is worse for guaranteeing compressor safety. Thanks a lot Randall and awesome question!
i wanted to see what you thought about putting the bulb before or after equilizer. i saw another tech video that said he had a problem with bulb after equilizer due to extra refrigerant from equilizer discharge affecting bulb temp. like a feedback loop that caused the coil to freeze up.
seems like there shouldnt be enough liquid coming out of equilizer to affect the bulb sense???? might be wrong.
thanks for reply
It would have to leak between the pin and the brass housing inside the txv, highly unlikely that it would be a significant amount. I see manufacturers for ac evaps factory installing external equalizer tube upstream of the bulb and also the way that techs try to install when given the opportunity which is bulb upstream of the tube but it is not like a freeflowing loop inside though, thanks Randall!
Why does TXV manufacturer not produce sensing bulbs with certain sized grooves/curves that can fit on certain sized pipes? Say sensing bulb fit 5/8. 3/4, 1, 1-1/2, etc.
Some manufacturers of evap coils that have the txv preinstalled press a groove into the suction line so the bulb has more sensing surface area, thanks!
thanks
Glad to help!
If the txv is not working
I will hace suction line on 60 and high side in 250
the cause of ekspansion is no ice flower why
Can you restate the question please, thanks?
😊😊😊😊
do not foam tape........use cork tape because you can remove cork tape for service work later
I have both in my truck, I know what you mean but I think that the tape looks cleaner. I do agree that cork tape is easier to get off, thanks Charles!
hi
So while researching a problem today I came upon a thread that contained a statement by a person mentioning that you should always mount the bulb UPSTREAM of the equalizing tube, so about 12" to the left of where you're showing here or next to that bottom bend although I understand that it's probably not the point of this video. The discharge of the equalizing tube can cause improper metering.
Great in-depth question. There are 2-3 schools of thought on that and one is that the txv is there to maintain a good system capacity. The other thought is to maintain a proper superheat for the compressor's sake. Some would say that you need the bulb to read the suction temp after the last device is installed which would affect superheat to make sure that superheat is not lost before reaching the compressor. Some would say that it is more important to fill the evap with the sat state as much as possible and that the compressor may be able to handle a small amount of sat state every once and a while. Others say there really is not much of a change in temp read on the bulb right before or right after the external equalizer. We also use txv's without the external equalization port which is worse for guaranteeing compressor safety. Thanks a lot Tie Dye and awesome question!