A/C Diagnosis-Sticking Thermal Expansion Valve (TXV, H-Valve) 

8-17-18 Don't forget about the SD merch you see above me^^^^^^^^^ 100% of my proceeds will be going to charity. When I have the list complete, I will be putting them up on my website (who we will be helping). Right now I have a pro life group called the Human Connection that offers free ultrasounds to women considering an abortion and of course a ton of other benefits for these hurting woman. I also have Light of Life Rescue Mission (homeless shelter in Pittsburgh) and a list of about 5 or 6 more. I think I will probably only go with 3 charities for now, to get the most help we can to these people.

This isn’t an AC video my friend, this is an AC CLASS. Thanks a lot.

I like the way you are unafraid to make mistakes in your thinking the problem through and then correct yourself. Excellent video - unrehearsed and unedited - stream of thought very good to see.

For who ever may be interested, nitrogen, a dry, inert gas, would serve much better for cleaning a system that must be absolutely dry in order to operate properly. Any moisture in the system will freeze and possibly plug the refrigerant line at the metering device, aka. The, or H- block. To do a jam up job that will give long lasting service a proper procedure must be done. After the system is cleaned and all connectors are closed up with both high and low side gauges attached to system, pull a quick vacuum with both gauged opened. Close gauges turn vac pump off. Connect vacuum line to nitrogen bottle, crack nitrogen, open high side gauge and bleed through system an open low side gauge and loosen low side line a little at gauge, and let blow a bit. At this time if you want to check all fitting, including schraders, pressure the system up to about 150 psi.,remove gauges with the pressure still in the system and check valve stems and any other connections to be sure no leaks, OR, reconnect gauges, both high and low, bleed pressure down to about 100 psi, close gauges securely and let it set while you have a beer and a smoke. 20 minutes or so. Check pressure on gauges. It should be exactly as you left it as nitrogen does not react to temperatures. Satisfied that you have no leaks, slowly release gas pressure through low side gauge and through r(e middle line on gauges. As the pressure nears zero but before it stops blowing completely, attach to vacuum pump and let the pressure reach zero. Tighten line and start vacuum pump. As the pressure begins to pull into a vacuum open up high side gauge. Pull vacuum for at least 1hr. Close gauges and stop pump. Leave it for a while. Time for a couple more beers, and a break. This step is very important the farther south you are, ask any shade tree journeyman. When you are well rested and cooled down, return to the gauges and see that the pressure has not risen at all. If not you can be sure the system is perfectly dry! If not dry the moisture in the system will boil off in a vacuum, and build pressure. If this happens simply start pump, open gauges and have another beer. Repeat this process until you are satisfied that it is dry. You are now ready to charge the system so connect to refrigerant oil and add 1/2 oz. per pound of full charge amount, unless you either drained the compressor or experienced a lot of oil in the repairs. This is one point where a call to a knowledgeable tech might help. Add exactly the ounces that is called for of refrigerant, but , always purge the open line up to the gauge manifold. Invert the container and open high side gauge. If you are using small cans, and it takes two or more, purge fill line each time. If you are confident that your charge is close then now it’s time to turn your container upright in order to clear the liquid, if any from high side gauge and disconnect from system and close off completely all high side lines. Finish the final balance through the low side with gas. Withe the engine running and ac turned to super cool the low side line should begin to sweat all the way to the compressor are very close. The actual cooling coming out at the dash is directly affected by the temperature in the car, however the capacity off an automobile ac is comparable to 3 to 5 tons of ac. Back in the day when air conditioning was an add on under the dash, it was not unheard of for it to spit out ice. You probably won’t see that but in the 30’s is possible. All of these steps I described are not always followed,but, if they are,you won’t have to worry about it for a long time.

Having worked in the automotive field for the last 40 years I have to say that every shop should have one or two guys totally committed to A/C diagnosing , there are so many variables and sequences of problems ,from seals leaking ,bugs clogging condenser cooling fins (especially up in northern Canada ) to you name it . My hats off to you , your diagnosis of the system was spot on only from education and probably #1 a few years of experience !! Well done and great video . Joe from Northern Ontario , Canada

I really appreciate these A/C-videos! The videos help me a lot in being more confident and not sending away some A/C-jobs to specialists but dealing with them myself! That not only helps me in leveling up my game but also makes customers happy when they are given faster and more direct service. I'm very grateful! Thank you!

Some great knowledge. The degree you broke this information down was nothing short of spectacular. It’s always important knowing the downfalls of the working of a vehicle.. and be that competent to leave “no stone over turned” to figure out the issues. Great video.. 👍🏻

@ScannerDanner - Another great video as usual. I hope you keep providing these videos to we, the "do-it-yourselfers". As always, thx for taking the time/effort needed to provide this video to us. It's much appreciated! Take care man.

Mate, bloody fantastic demo vid. Loved the way you kept your cool, thought things out. Went through step by step, with limited tools you had available to work with. Your process of elimination of potential problems leading up to the TXV. Checking work done by previous techs was a good move. You nailed it, excellent. Real life problem/repair. Not edited demo in a class room with pretend scenarios. I now know how to diagnose a faulty TXV. Cheers from down under. 👌🏻👍🏻👏👏👏 🖐 🇦🇺

Wow! Best AC video on RU-vid that I have seen ever. Love the way you diagnosed the problem by process of elimination. Excellent job! Love it.

I watched a lot of video about AC problems, but only this video that fixed my AC. Thanks man. I love how you find the problems and reasoned it why like this, like that made us learn how to think. I love how you admit mistakes and learn from it to keep forward to find the problem.

Purely simple, straightforward and actually shows what can be done in the field. Am so thankful for your great work.

Another brilliant video, Paul. Over the years it is getting harder to find stuff I haven't seen before, but this was one I somehow missed.

Thanks Danner, really appreciate the last section where you release as much pressure as you can into the low side. Actually, I ran into this particular problem while doing some AC work, I finished my work and disconnected gauges and Wow a whole bunch of Freon still in the lines, I said what the heck, so now I understand better, great Video Paul, as always keep up the great work, much appreciated!!!

Great post! Real time diagnostics , thinking through possible problems is what us techs due until we find the true problem.

Now here is a real teacher that can admit when he is wrong and correct the problem. I'll watch Paul any day. I always learn from him. Thx!

Nice job Paul! Loved the manifold gauge tip at the end.

Very good video. I really like how you reasoned your way through this one! Keep up the good work!

Great video paul. There's not a lot of good videos on ac mechanical component failure diagnosis, this information is invaluable. Mighty convinient the recovery machine got fixed just in time and off camera haha.

Im doing a fair bit of AC work at the moment with it being the season for it, so great to see quality content videos like this. Liked your thinking out loud bit whilst trouble shooting, good job thanks alot as always 👍

Thanks for this video. One of the best I have seen with real time troubleshooting! Explain every question I had

I love the fact you take us on the journey of troubleshooting. I know I do a similar exercise using what I am seeing while adding what I have seen in the past to come to the final resolution. Brilliant! Never be too proud to say “I was wrong.”

Good for Pete! I was the one that commented on his weight loss 👌🏽👌🏽👌🏽💪🏽💪🏽💪🏽🥊🥊🥊

I like the way he talks threw the thought process in trouble shooting the A/C system it takes experience to know what you are looking for

Paul, being an old GM A/C guy spot on video, love how you traced it down....

Just saw this in 2019, Paul excellent troubleshooting skills & finally solving the sticky E valve issue. Much love from Ghana 😊

Outstanding trouble shooting mate! Many armchair quarterbacks seem to have forgotten what trouble shooting means. As youve pointed out in the video there are several locations where the AC system could fail and isolating that area of failure is the challenge. Great video which also pointed out the other potential culprits that need to be checked out when servicing the system.

Very cool. Like the way you explain your reasoning and logic behind it. Thanks for posting.

I just want to read through it. I know it will help. You have helped me so much already. even with your free channel. it's unbelievable. I been following James also.

Being able to trace the lines is critical in finding system restrictions, but as you showed, sometimes even the best diagnostics guys need to throw a part into the mix once in a while. It was an educated decision, though, and that's what counts! Awesome stuff, Paul. :D

Good informative video! Admit the possibility that you might be wrong, learn from it, and move on! Thank you.

this video is 5 years old but i can't help but mention that the fact that you have a diagnosis but then find it to be incorrect and that you actually say so in the video. the process of elimination is valuable as well. i wish more were like you on youtube.

I like the guy out for a cruise on his rider and stops by for a visit. Keep it real Danner you have way more knowledge than most and still admit if you are wrong

Great tip to bleed off the pressure in the high hose. Thanks.

thanks for the video. i would call it an educated guess , seeing how the TXV is the smallest orifice in the high pressure side. and most of the time a restriction is gonna be found at the smallest orifice. always good practice to replace the dryer aswell. good call with the diag.

Thank you for the lessons you keep bringing us. Please keep it up.

Love the gauge set purge tip Paul. Thanks!

I love how you bend the textbook rules to teach and prove your methods. "Never use shop air on an A/C system" "Never use a test light on computer controlled systems"...Thank you for that lecture 🙏🏼...You almost used a Scanner on this one 😄

You can also cut the engine back off after the ac compressor has ran and see how long it takes for both high and low side gauges to balance back out. If it takes too long or maybe it never balances back out there is definitely a restriction. An orifice system usually balances out in less than 1 minute. TXV may take longer because of its changing flow rate. We saw a restricted TXV causing over 400 PSI on the high side and like 50 psi on the low side once which made that a very obvious closed non working TXV. Another good one Scanner, looks like you've been hitting the weights.

There is a lot to learn in each of your videos. You are a good person. You share your experience with us.

Richard's "Mobile " Auto and Air in Tampa,Fla. says Hello and keep up the great work you are performing for the benefit of D.I.Y.'s and Auto Technicians. I decided to subscribe to your channel today because I have been watching your videos and feel a need to support your work and efforts. Thank you.

You're a very sharp guy. The only thing that I would add is to jumper the low pressure cutout switch and let the system run even if it's in a vacuum. If the low side is in a vac and high side is normal= restriction. If High and Low are both low=undercharge. restrictions usually frost the extrerior of the line at the location of the restriction as well, this would be harder to discern at with an expansion valve attached to the evap, as an undercharge would freeze part of the evap(possibly suction line as well). In a system with an orifice in the high side line a restriction would freeze the line at the location of a restricted orifice. I have 15+ years of HVAC experience, and I'd say that I was impressed by your diagnosis.

Short Cycling systems move oil (Banging off the Low or High limit). That is why your hose was full of oil. I'm HVAC Tech for a living and when I've had a TXV fail I very commonly have a liquid hose full of oil. I usually find a lot of oil at the TXV as well.

This is the kind of hands on instructions I would deem as "Professional"! I surfed U tube several times and could not satisfy my queries on A/C issues. I have a 2002 Ford f350 7.30 powerstroke with A/C issues. After much research, I find a similarity in the A/C control procedures as elementary as the any other model with issues to be confronted. This video is highly educational to any shade tree mechanic in any country. I come from the country of Texas and I don't play games! Well done ScannerDanner!

Hey scannerdanner. I love your motto. "Don't be a parts changer" I used a few videos to study for my ac ase exam and I pass. Some of the point your talked about was in the exam. Thanks bud.

Totally good call on the TXV the good practice would be to change the dryer too and I am sure you know that I would blow out the evap with nitrogen after putting in the new txv leave the outlet unplugged would make sense why it took forever to get the low side to come back up

Wow, amazing how much he looks and sounds like my favorite character Jax Teller from "Sons of Anarchy"

I greatly appreciate your enthusiasm in everything about diagnosing and fixing vehicles. I understand talking out loud the many thoughts going through your mind is the way you use to help yourself diagnose problems, but it makes collecting the information much more difficult. On every one of the many videos I have now watched, you make what appears to be a specific highlight about a situation or final diagnosis, only to then change your mind and or add or subtract from the comments you made seconds or minutes previous. Just as I'm telling myself to remember certain important points by what you say, you turn around and change your analysis. I talk out loud to myself all the time, but when I teach others, I try to take a few moments extra and ensure if what I'm about to say, is the message I want to convey. Thanks very much for sharing your knowledge and time.

Thanks paul the way you teach is phenomenal it's so simple even a lame man can understand easily you are a blessing to every diy person around the world

ScannerDanner is a real intimidating name that made me actually avoid the channel...smh... what a fool I have been this is one of the best tutorial channels on youtube.

Awesome video. Much to fall back on. Now time to change out expansion valve

Year of experience putting to the test. You are a good AC mechanic. 👍

I bet there was a proper recovery done on this 😉 😂😂😂😂😂 That’s alright the EPA does allow “trace amounts” to be vented to atmosphere

It is normal to have a lot of oil in the liquid line with a restriction like that. Most of the oil should stay in the compressor under normal operation. It's better to have a little too much oil than not enough

Hey Paul your son is doing a great job filming! ALways nice to have an extra helping hand. Take care -Glen

Great job guys! Paul, thanks for taking the time to explain the flow route through the system, that really helped. Great information. Thanks!

With a clogged expansion valve/orifice tube, it will cause the compressor to over pressurize on the discharge side therefore causing clutch to slip. When clutch starts slipping, excess heat builds and destroys bearing.

21:46 the condenser is parallel flow, so I think the bottom could have been full of oil and you would never know by blowing air through it.

Awesome instructor! I appreciate your sharing of automotive service, repair and troubleshooting

Great example of a troubleshooting scenario. Intuition and failure are key to understanding problems and even other operating conditions. The internet is packed with experts who get it right (in their edited videos) every time. This is how to be a real expert. I don’t work on cars but other machinery and live musical set ups. I’m wrong a lot. But then we know what it’s not. Your process and openness in sharing it is really well done. BTW I think my daughter’s expansion valve is bad in her RR sport. I think I’ll be a “parts changer” and see if I’m right!

I can only imagine how Pete "recovered" that system haha.

"Recovery machine" hahaha! Judging by those goatees, that refrigerant got leaked onto Pittsburgh!

Love the video! I am a plumber by trade, so troubleshooting systems isn’t new to me, and your talking through the problem and adjusting your analysis is beautiful to see. I have a 2006 Durango that is having AC problems, and I suspect that it is an expansion valve or other restriction as a mechanic was stumped last year as to why the pressures were right but the system wasn’t working. They were in a hurry and I doubt that they caught the signs of a blockage or cared about tracking it down. My manifold gauges arrive in two days, so I hope I can track down the problem and then let someone with the right equipment evacuate the system and refill it

Thank you for sharing this information and helping me to troubleshoot my 2013 Nissan Altima. Which has a full charge after an accident but it won't stay cool. Even though the Dealer ship did a full recovery on it twice.

I recommend always bleeding the air out of the lines after hooking them up. Ac systems don't like contaminates.

Didn't see you purge the air out of your refrigerant line when you started to add charge?

Just helped me figure out a Cummins with the exact symptoms . Thanks!

Awesome video! Thanks for the heads up on the compressor oil being over serviced.

still needs a receiver-drier.

Well if the expansion valve is plugged up with debris, then the system is contaminated and replacing the valve will only delay it from happening again (IMO).

Great video, It all has to do with been a great tech and troubleshooting experience. I learn a lot today. Thanks.

Sir, I'm am old coot that takes on some of the toughest motorcycle and early hot-rod trials an exercises and I must say I am Impressed at your skills at going about this, admirable. Thank You !

Another superb video, Paul. Imagine the poor souls who unknowingly go into the auto parts store and come out with the $30 bottle of AC Pro thinking they're gonna save themselves real money. They connect it up, see the really low pressure and start filling it until the low side pressure goes to that green arc! Imagine how high the high side pressure would get. Likely not using any safety glasses and when that compressor safety vent blows they get a face full of refrigerant and oil. Ouch. One question...after blowing out the condenser and the evaporator with shop air how do you know you still have enough oil in the system?

i have a flir thermal imiging camera ,ideal for restrictions difference in temperatures

Hi Scanner Danner, thanks for the video. I have watched a few of your videos on scanners and enjoyed them. I owned an automotive air conditioning & radiator repair shop in Dover Delaware from 1973 to about 2003. Then I sold it to an employee and it is still open today. Some shops use charging stations to charge vehicles, I did not like them because the were too costly and added complications. I used a plain gauge set like you used. For years it was a R12 gauge set with 1/4" flair fittings. They had pressure temperature relationship numbers for several refrigerants on the inside rings and PSI/vacuum on the outer ring. I had a refrigerant identifier and used it before refrigerant recovery. We had a recovery machine for R12 and another recovery machine for R134a (Robinair). I always used gauge sets to check out and service cars. I always used new refrigerant to top off working systems and after repairs. That way I new it had good dry pure refrigerant put in it. The over charge of oil is common for beginning A/C service techs. Also I was very careful about not having air in my A/C gauges. I would want the gauges to either have a vacuum or refrigerant in them. So I bled them a lot. If you had air in them and hooked up to a vehicle and the suction side went into a vacuum it sucked the air out of the gauges. I wanted vehicles I charged to have 0% air. Some rebuilt compressors were not always marked as to how much oil they had in them. If we had any questions we would drain the oil from new compressor into a clean container to see how much it had in it. Then make adjustments to how much oil it had and seal it back off. The compressor could then be put on the vehicle. When I started A/C work many compressors had oil in the crank case or in the belly like a GM A6. Now most get lubricated buy returning refrigerant. Sort of like a 2-cycle engine gets oiled. When ever we changed a compressor, we always flushed. We flushed all the hoses and both heat exchangers. We would try to flush out in both directions. We would blow a bunch of solvent into a component and some how catch it with a heater hose going off to a catch can or catch it with a shop rag dripping into a drain pan. Then we would pop the item dry. Finger on and off outlet while blowing with air with a rubber tipped blow gun. I early on used Nitrogen to blow out components and to leak test. I had a setup with 175 PSI pressure release valve. For years we used Mineral Spirits to flush. Then we changed to more expensive flush solvents for R134a systems. Then we would put the compressor in service with the right amount of oil. We did not flush through compressors, dryers, accumulators, expansion valves and suction valves. Extra care would be taken to a hose assembly with a muffler in it. We had a large parts inventory and there were years when I had 5 techs. We installed air conditioners, serviced air conditioners, repaired A/Cs, and repaired radiators. We did a lot of large trucks. I even went away to truck refrigeration school in Syracuse New York (Carrier-Transicold).

Awesome tip Dan to pull out as much out of your hoses before disconnecting - at 150 psi that's a lot of refrigerant - I just learned what not to waste thank you so much.

I can tell by the flow rate out of the can.. Any restriction they empty slow. the second I see that. the TXV or Orifice tube is clogged up...

Fantastic, I'm working on a Tacoma and this video help me zero in on the problem. LOTS and great tip and tricks. THANKS for posting, your the man!!!

Good afternoon family and thank you very much for the valuable information and for your time. 👍🏼

I appreciate you expressing your train of thought. I was able to understand the process of elimination much better. Thank you.

Though you say you were mistaken, you did the right thing by testing/ diagnosing possibility of symptoms. That is being a good mechanic!!

Future Auto Tech in a A/C and heating class, here watching this 6 year old gem!!! Thanks Paul for everything!!!

Best HVAC diag video I have seen, nice job!

Awesome video as always Mr. Paul. Thank you.

I really like those gauges. Great video btw. Great troubleshooting train of thought.

Thanks brother for posting this video ❗️ Helped me and others for sure ❗️

Mr scannerdanner thanks a lot for a great video, I love the nice tip on how to let the pressure out of the gage s and hoses.Have a great day, GOD bless.

Dude you are a great mechanic and do a fantastic job of explaining the AC system. I didn't know shit about an automotive ac system until your video. I live in Kelowna British Columbia Canada and it gets as hot as 100 + degrees here in the summer. My wife's car AC doesn't even come on at all. I'm going to buy the proper tooling and fix it myself. She drives a 2007 Chevy Aveo. You are helping folks help themselves.

Nice illustration,real nice.

some real handy tips, thanks.

You are doing just what my mechanic does - start changing parts until it is fixed- no loss to you- the customer pays it all.

Everything you said is on point. You just weren’t impatient enough for the instant gratification crowd!

Sir I wanted to recognize your leadership capabilities. I heard you say the words, “I was wrong.” It take a true leader to admit that. Thank you for your videos they are amazing.

Good diagnosis. It's such a pain to try and explain to people that rarely just adding freon fixes everything. Its like with power windows when customers say that"It just popped off track", ignoring the reason it did that in the first place. And a thermal camera for finding restrictions is nice to have, just realized I need one....

Thanks. I just subscribed. Better than most and you are not afraid to admit to a missed diagnosis. Glad to see that.

Thanks so much danner i have same issue at my mazda right now just ordered txv valve based on your video , i looked alot online and found only your video that talking about this issue thanks so so much for being a huge support and guidance

Another great video, thanks for everything that you doing for us!!!

Thanks for the video guys!

Excellent vid, thanks! SD, you called it right because it had to be that valve by the time you got done. You eliminated all other restrictions and the potential oil overfill, and the compressor was making plenty of pressure and suction. I thought the restriction might be desiccant from a failed receiver/drier. I've heard of it, never seen it, but your procedure would have revealed it. Had to be the valve. So you called it right about halfway through but made sure before you stopped and put a valve in it, like a real professional does.

First off I'd like to say great videos. Wish these were around when I got into the field. After dealing with all the bullshit and even having my own shop, I went back to school for industrial automation and got out of this mostly thankless career. Dont get me wrong you have great customers that appreciate a good honest experienced tech but for the most part we are taken for granted because it seems like everybody's brother uncles friend works on cars and what alot people dont understand is you get what you pay for. I worked on a lot of jeeps which should have the same thermal expansion valve. Everytime we had the same issue we tapped on the expansion valve with a hammer and it would open. They are notorious for sticking and tapping on it frees it up and pressures go back to normal right away. Replace the expansion valve anyways cuz it will stick again.