Frozen Evap Coil Troubleshooting: Liquid Line Restriction, Low Airflow, Low Charge!

[@acservicetechchannel]

-My Paperback, E-Book, Workbook, Quick Reference Cards: www.acservicetech.com/store -E-Book: play.google.com/store and search "AC Service Tech" -My Paperback and Quick Cards: www.amazon.com/shop/acservicetech -Support the Channel: www.patreon.com/acservicetech -Tool List: www.amazon.com/shop/acservicetech -Facebook posts every other day! facebook.com/acservicetech -Our Articles: www.acservicetech.com/articles -Our Quizzes: www.acservicetech.com/quizzes Related Videos: Fast Check for Low Refrigerant Charge: kzbin.info/www/bejne/hZbOlZqhrJmXr9U Explaining Superheat and Subcooling to Your Apprentice! kzbin.info/www/bejne/aISodZhmq52Jhrs HVAC Delta T Explained! What Temperature Should it be? kzbin.info/www/bejne/b52nnWiZm6uGsNU Saturated Refrigerant Temperature Basics! kzbin.info/www/bejne/fHzceKh-gLqBptE Total Superheat Method! kzbin.info/www/bejne/qWqsYpSMqsyXobs Checking the Charge Tools: Yellow Jacket Refrigerant Gauge Set amzn.to/2aenwTq Refrigerant hoses with valves amzn.to/2aBumVI Yellow Jacket Gauge set & hoses amzn.to/2vLVkV9 Yellow Jacket 4 Port Manifold w Hoses amzn.to/2BkuGIq Digital Refrigerant Scale amzn.to/2b9oXYl Ratcheting Service Wrench amzn.to/2dGV4Nh FieldpieceSMAN380V Digital Manifold Set - amzn.to/2yqzBX6 FieldpieceSMAN480V Digital Manifold Set - amzn.to/2ytvGZL Fieldpiece SDP2 Digital Psychrometer - amzn.to/2nniMVR Testo 549 - amzn.to/2X0jJVj Testo 550 - amzn.to/3bIQvhS Testo 557 - amzn.to/2ylgeyw Compact Ball Valve for Refrigerant Hose amzn.to/2KUisW8 QuickDisconnect 90 for refrigerant hose amzn.to/2MMtVcg RectorSeal Bubble Gas Leak Detector amzn.to/2ckWACn Fieldpiece ST4 Dual Temp Meter amzn.to/2wc1ME3 Fieldpiece Bead K Type Temp Sensor amzn.to/2DBwKfs Fieldpiece Wet Bulb Temp Sensor amzn.to/2RRI7Tw Fieldpiece TC24 Temp Clamp amzn.to/2qHLyjZ Electrical Diagnosis Tools: UEI DL389 Multimeter amzn.to/2xAdaJf UEI DL479 Multimeter with temp sensor amzn.to/2jtsUbJ Magnet Jumpers- amzn.to/2PyKPQZ Alligator Jumpers- amzn.to/2PxqJXn Irwin Wire Stripper/Cutter/Crimper amzn.to/2dGTj2V Vacuum Tools: JB 6 CFM Vacuum Pump - amzn.to/2nqbvo8 CPS 4 CFM Vacuum Pump - amzn.to/2DxgPwY 1/4" Appion Valve Core Removal Tool - amzn.to/2uYr8WL 5/16" Appion Valve Core Removal Tool - amzn.to/2JHmfbP Appion Blue 3/8" to 1/4" Vacuum Hose - amzn.to/2uYlVyc Appion Red 3/8" to 1/4" Vacuum Hose - amzn.to/2uYg6Ro Yellow Jacket 1/4" by 1/4" 3’ hose - amzn.to/2umtcod Appion 1/4" by 1/4" and 3/8” hose - amzn.to/2Zyxzx9 Uniweld 1/4" by 1/4" 2’ hose - amzn.to/2GFov1Y CPS Vacuum Micron Gauge - amzn.to/2v1nM3O JB Vacuum Pump Oil - amzn.to/2mGrlXy Flaring Tools: Yellow Jacket Flaring Tool - amzn.to/2OBxGlM Spin Flaring Bits 1/4", 3/8", 1/2", 5/8", 3/4"- amzn.to/31BCs8Z Yellow Jacket Flaring Tool with Set Depth - amzn.to/2QIKsQH Yellow Jacket Torque Wrench - amzn.to/2NRR68Q Uniweld Swage and Flare Kit- amzn.to/2T55jyn Nylog - amzn.to/2MLJcch Ridgid Tubing Cutter - amzn.to/2DnjjR1 Wolverine Tube Reamer - amzn.to/2QGLyMV Swaging Tools: Manual Copper Tube Swage/Expander- amzn.to/2WRPa1M Spin Swaging Bits 1/4" to 7/8" for the Drill- amzn.to/2YQwwqS Uniweld Hydraulic Swaging Tool- amzn.to/2MlrI8m Uniweld Swage and Flare Kit- amzn.to/2T55jyn Uniweld Hammer Swage kit- amzn.to/2CzWMMU Uniweld 3/4" Hammer Swage- amzn.to/2CzXsSs Uniweld 7/8" Hammer Swage- amzn.to/2Mja5WE Uniweld Multi-Size Hammer Swage- amzn.to/2T3Cx1b Brazing Tools: Air Acetylene Torch setup - amzn.to/2aQalsb 15% Silver Brazing Rods - amzn.to/2gVLyLc Ameriflame Oxy Acetylene Torch Setup #1 &#2 Tip - amzn.to/2SRm3JF 40cu B Tank to 10cu MC Tank Acetylene Tank Fitting - amzn.to/2GxZZPi Nitrogen Regulator - amzn.to/2bXdR5f Uniweld NitroVue Flow Regulator - amzn.to/2GnsaAo Uniweld Nitrogen Flow Meter - amzn.to/2brvoBg Stay Brite #8 Silver Bearing Solder and Flux - amzn.to/2XIDJsY Aluminum Braze Rods - amzn.to/2IGNMu Refrigerant Leak Detection Tool: Accutrak VPE Ultrasonic Leak Detector amzn.to/2nFYKVe Shop through Amazon! Your Purchases through Amazon provide a means for channels such as mine to earn advertising fees from all purchases after clicking through. Prices are the same as normal.

[@jericosha2842]

As a new tech this is ESSENTIAL everyone. We need to actually understand this instead of blindly dumping in more refrigerant "to see what happens." Thanks Craig.

[@geofferyhawk7575]

Thank God someone who finally talks about the problem

[@marvinostman522]

I am looking at you videos since I am under preoperative isolation. I find them very helpful. You do something that so many videos and seminar instructors fail to do. You explain "why." When you understand why it is easier to remember the "what."

[@metaltera86]

New tech here. Been installing for almost a decade and now just getting into service. Ran into my first failed TXV. R410a system on a 65 degree day with head pressure of 325psi and consistent suction pressure of 80-85 psi. Super heat was around 40 and sub cooling was around 30 and indoor TXV had a temp drop of almost 30 degrees. Half the coil was frozen over and evap coil was clean as well as filter. Safe to say it was the metering device

[@acservicetechchannel]

Yup tell tale sign when 1/4 to 1/2 of the evap is froze and the system has been running a long time, thanks!

[@harh3101]

A word of gratitude for the teaching, I am waiting for my first book from you to arrive.

[@premarora7572]

Thanks!

[@acservicetechchannel]

Thank you so much! Hopefully my video has been a helpful resource for you!!

[@mikev.1034]

👍👍👍👍. Just from this video I now know and understand how to calculate subheat & subcool. I do plan on buying your book soon

[@acservicetechchannel]

Awesome, I am glad you enjoyed it!

[@abegailkadam2171]

Hi, very well explained in detail, I thank you from the bottom of my heart, and believe me, I have learned and got so much practical and theory information from you sir. 👍🙏

[@acservicetechchannel]

Glad it was helpful!

[@pizzle1011]

Thank you for the video! The book is a great reference! 👍🏾👍🏾

[@acservicetechchannel]

Awesome to hear!

[@paulrozinski1488]

As always , enjoyed the video. For those of us who have purchased the book, could you preface future videos with the corresponding page numbers ( I’m sure it might boost book sales👍). Thanks again.

[@randyumfleet8694]

Exactly what I was looking for my issue. Great Job!

[@honestman276]

I have enjoyed your lesson on troubleshooting why ice is on an evaporator coil. Thanks from Bangladesh.

[@acservicetechchannel]

You are welcome! Thank you for watching!

[@nikkuthomasabraham3784]

You r a good teacher. Really appreciate your effort. Video is very simple and up to the point. Even a beginner could also grasp things very easily. Welcoming more more videos like this. Soon I would like to purchase your book too

[@acservicetechchannel]

Sounds great and there is an outline and sample pages of the book at www.acservicetech.com/ac-book thanks!

[@timrob0420]

Have a new install, American standard 13 SEER with piston orifice. Installer called saying it was immediately shutting off on low pressure. I go out and bypass low pressure switch to observe. System immediately starts to drop low side pressure to around 50psig with a superheat of 3°. Indoor temp is 79°. Suction line temp literally drops to 1-3° and freezes in less than two minutes. All registers open, good airflow. It really looks like line restriction but only thing that looks off is the low superheat. Tested temp across drier, good. Even pumped system down to look at piston and screen, both clean. No kinks in line. When I observe I see frosting occur at top of coil near suction “manifold” that feeds back to suction line. Both service valves are open as well. I’m a little stumped on this as normally I’d think I’d see a high superheat. Unless if part of coil is restricted and causing it to flood but not be able to keep up with capacity? Some help would be appreciated.

[@robertl.7657]

Great video Craig, waiting for this one long time!l keep the good work!👍

[@acservicetechchannel]

Awesome and I am glad you appreciate it!

[@StOckERT19]

What if I have normal subcooling, but only 5 degrees superheat on a r410a rooftop unit with a txv? Could it be the txv has failed? Evap coil temp is 30F and freezing intermittently. Any help would be great thx. Airflow appears normal but doing more testing tomorrow.

[@Froggability]

Interesting. Another couple of reasons for icing - blocked filter / fins - air handler capacitor low Mf - 1 fan speed dead - setpoint too low; cooling in cool weather. - condensor requires "head pressure controller"

[@acservicetechchannel]

Absolutely, I just did a video on 20 causes of low airflow, thanks!

[@workingshlub8861]

had a call last week ...tenant had all but two supply vents closed and the couch was blocking the return air vent...

[@picklerix6162]

Don’t forget a contactor that is stuck closed with welded contacts. I have seen that cause a frozen evaporator too.

[@MC-mq8mh]

As always I appreciate the video, very educational.

[@acservicetechchannel]

Thank you for your support!

[@salvatoremagarelli4491]

ALWAYS AWESOME ADVICE GREAT JOB CRAIG

[@acservicetechchannel]

Thanks Salvatore!

[@zekenzy6486]

Great Video. Thank you for sharing. Is Roof top unit commercial checking the same resident hvac unit ? Thank you.

[@acservicetechchannel]

Yes as long as the ports allow for superheat and subcooling measurements. Sometimes they only give you discharge pressure and a chart supplied by the manufacturer, thanks!

[@Xmonders]

Thanks for the Lesson👍.....always greatly appreciated!

[@acservicetechchannel]

My pleasure!

[@jmichel70]

Thanks for all the videos

[@acservicetechchannel]

Glad you like them!

[@Pablosdiyprojects]

Hi, Craig. The technician thinks the TXV valve is not expanding correctly so is not good. Because of that he do not recommend to change just the TXV valve, instead he wants to install a Nex compressor, evaporated and condenser, so that way the system is going to work ok. Is that right? I don't think we have to change the entire system just because the TXV valve is not working properly. Can you help me please, explain me this . Thanks very much Craig.

[@davidestrada5488]

Great job as always sir!👍😁

[@acservicetechchannel]

Thanks David!

[@acservicetechchannel]

-Do you have what it takes? Quizzes: www.acservicetech.com/quizzes -Our Articles with many descriptive pictures: www.acservicetech.com/articles -Facebook posts every other day! facebook.com/acservicetech

[@martinlavoie4002]

Awesome video. My question wold this wok on a Automobile set up? I have rarely seen a frozen coil in a car but remember seeing a beetle doing that to me

[@pradeepbansod3334]

Hi, thanks for the super video. I am a homeowner, not a tech. Recently I helped a friend who had a frozen evap coil. I found the compressor was never shutting off, and traced it to a faulty thermostat (old mercury switch type). After replacing the t-stat all seems to be OK, but, question -- is a constantly running compressor one of the possible causes? Or might there be other issues that need to be checked by a tech?

[@jashua2089]

Awesome video!

[@acservicetechchannel]

Thanks for the visit

[@bryontharp5790]

What should be the lowest low side temp on normal conditions before freezing up thanks

[@marvinostman522]

I have a question that isn't related to this video but I hope you can answer it for me. When you look at a troubleshooting chart one category is amp draw. I have never found anything telling you what the amp draw should be. It's always "the amps are low, amps are high, amps are about what you would expect." I have heard that the amp under normal conditions should be about 75% of the data tag. Is there something more accurate?

[@rcorona8364]

Hi, I’m currently an hvac student and I was thinking about getting your book to sharpen up and help myself get through this course easier. I went over to your website and tried a couple quizzes and I’m wondering if they follow your book? Like as I’m going through the book can I go and do those quizzes and expect to know the answers or do I have to finish the book and then do the quizzes? Or are there small quizzes in that book? Or do I have to buy the entirely separate work book if I want to make sure I’m following? Thanks.

[@acservicetechchannel]

The 1,000 question workbook comes with an answer key and that would be the best test of knowledge for our book. We also have a 100 video list that correlates to page numbers in our book at www.acservicetech.com/videos. You should be able to answer the quizzes that are related to the topic, thanks!

[@karmsirrah8173]

It's a good book I'm learning it to how long you been in school

[@The1realro]

Where does one take measurements for delta t in a air handler with no return box below the coil as shown in the video. Under the coil is the filter and then nothing. Supply box is also just an inch or two of plenum.

[@timpfirman3788]

Newer tech here, just ran into a 410A system yesterday with a low superheat of 10 degrees and high subcooling of 22 degrees. The bar inside was only getting 65 degree supply air minimum, I believed this to be an overcharge problem however after taking 8 -9 oz of refrigerant out, the system would not correct itself and still had the same readings.. condensing unit is on the roof as well. Indoor unit has a TXV, could this be a restriction?

[@timothymullis3225]

If you have a heat pump, can you put it in heat mode to thaw out a frozen coil? Or is this bad for it.

[@officerkrupke4966]

Yes, but you would have to pull the air filter out first to keep it from becoming a soggy mess, and you would have to have a plastic tub under evap to catch all the water dripping off the ice. Drain line is for normal condensation.

[@mikelewis4260]

Question for txv bulb placement on a vertical pipe should the little pig tail be facing up or does it matter. Thank you in advance for the response. Love the videos.

[@get2it7]

4 years and still no response 😂 did you find the answer yet?

[@chesstime356]

As always nice videos

[@ddcws1]

What’s considered high subcool with a fixed orifice? If you check a system when outdoor ambient 60 indoor 70 wouldn’t subcool pretty high because the refrigerant flow depends on load. TXV is a little easier to diagnose with restrictions but fixed orifice can get confusing at times.

[@acservicetechchannel]

David, thank you for your continued support! So you don't have to pay as much attention to subcooling when you are past if the system is too low on refrigerant and distinguishing between low airflow or liquid line restriction. It will be pretty distinct with a piston. Low superheat and high delta T means low airflow and high superheat and low delta T means liquid line restriction. With a fixed orifice you need to pay more attention to the superheat. Each system will run a different subcooling, it may be 10 or it may be 18 or 20 degrees but because we can't set the charge with subcooling and only by superheat we need to pay more attention to superheat. For a system with a TXV, the superheat and the subcooling will both be more known so that is why it may feel easier to troubleshoot those, thanks!

[@abdulhvac2395]

Thank you for sharing very nice

[@acservicetechchannel]

Thanks for visiting

[@dylandrymond3951]

If the coil is not frozen can you still check subcooling on a piston for a low refrigerant charge as you did in the beginning of the video?

[@MrRheo29]

Yes

[@techbullet1020]

Hey Craig love your videos. Did you make any Animated version about HVAC Troubleshooting and Learning tools/app like the one shown in this video?

[@johnnyabad7832]

Very informative! Do you have training books that i can avail?

[@acservicetechchannel]

Yes available at www.acservicetech.com/store thanks!

[@tylerfabish5578]

8:02 couldn't you also have moisure in the system? A water droplet could freeze on the piston/orifice and cause a restriction. You could thaw the coil and the problem may go away. The only way to fix this is to recover and triple evacuate. Correct?

[@nilborne1]

Would really enjoy a video on variable frequency drives.

[@acservicetechchannel]

Thanks for letting me know!

[@edwinjewell5359]

Hell No.

[@ronselectrical8177]

If it was liquid line restriction on the filter dryer wouldnt putting probes on both sides of dryer tell you a temp difference indicating it was the dryer?

[@Froggability]

Correct but it's very unusual

[@adolfomedel254]

Hey Craig!! Great videos man!! Quick question. Is it common or possible that the capillary tubes, i think they are called distributor tubes, to become clogged rather than the metering device itself?? I ask because often I fine, some of the capillaries are frozen and the other are not. From my understanding, they are all supposed to frost evenly. Im not sure I've seen any videos where you have covered this question, but if you have id love todee it. Thanks!!

[@Froggability]

Correct, sometimes header tubes block, the symptoms are cold spots in unusual places. The biggest cause I found was runaway filter media

[@jimbola77]

awesome!!!! thank you for sharing.

[@acservicetechchannel]

Glad to help!

[@other91solution50]

Thanks for the info dude.. Awesome..

[@acservicetechchannel]

Glad to help!

[@ryanduhaime9086]

Hi Craig, a fellow tech was told to change a condensing unit. The same problem still happened after. (Normal split system). Comes on and shuts off immediately on the high pressure switch. (600 psi). He thought he might have had a restriction Txv stuck closed. He heated up the bulb and it opened up and ran fine. Does this make sense to you? Thanks

[@get2it7]

It means that the txv bulb refrigerant charge ran out and the txv needs to be replaced

[@SombraLocs]

Great video!

[@acservicetechchannel]

Thanks a lot Familia Sanchez!

[@terrytugwood7848]

Hi where can I get a hard copy of your book I’m in the UK , thanks

[@acservicetechchannel]

We would be shipping from the US. There is an international shipping calculator at www.acservicetech.com/store thanks!

[@raulrobles2961]

If your low on sub cooling would that also mean your super heat is to high?

[@acservicetechchannel]

on a system with a fixed orifice yes but not necessarily on a system with a TXV. It will depend on how low the subcooling is before it affects superheat, thanks!

[@jimmydavis6846]

what if negitive subcool?

[@Achabab]

I enjoy this video, I find my self need watch it again and again.hhhhhhh, but next time I need bring my note and my pencil......thank you very much for this video. And waiting to next video can show the example for real trouble shootings :):):)

[@jorgerodriguez5828]

Why the evap. Fan not working at all?

[@zipperdingo6385]

You are just amazing

[@MrGabriel1973]

can u make another video with 134 pls?

[@andresperez-wc8ty]

I dont understand why the suction line gets warmer with a liquid line restriction that leaves the evaporator with little liquid to boil yet its the opposite effect with the suction line freezing when refrigerant is low leaving the evaporator with little liquid to boil. Can someone plz help me uunderstand ? ty

[@vica5184]

Do you have this book in Spanish?

[@acservicetechchannel]

We have an ebook in spanish presently at www.acservicetech.com/store and also on google play, thanks!

[@IsidroZuniga]

Correct me if I wrong 35 degrees would be low super heat

[@kevinblasingim7613]

Also don’t assume just cause your split temp is low you have a liquid line restriction. Always verify blower speed. Some guys install a 4 ton furnace on a 1.5 ton AC and never adjust the blower. Literally just seen this today and the system was this way for 3 years. I don’t understand why but wasn’t our work. If your new in the trade the best advice I can give is literally start from basics and work your way in. Never jump too far ahead. You may be chasing something and the problem is just a few closed vents or something.

[@joemcorbett]

If you watch the condensate drain with the indoor fan on and CU shut off, you can see when it is defrosted as soon as it stops dripping. Don't add any refrigerant until all dripping has stopped 100%.

[@eclipse369.]

You going to watch it for hours? If you got time defrost it. If you don't come back latter while it's runs dry. Do they wanna pay for defrost or for trip back. If I'm not too busy I don't mind being paid to play with water.

[@kevinlawson8124]

Also, thermostat set a too low for desired temperature!

[@keepback343feet2]

Why am I still up¿

[@keepback343feet2]

Why am I still up?¿

[@smacleod69]

Some of those reading may just mean that you have low refrigerant charge in the system and not necassarily a restriction.

[@datacentermechtalk6852]

Bad fan ,clogged Filter, low charge or clogged drier or metering device stuck closed

[@soloralphlauren2731]

R4-Tenay

[@NorCal-refrigeration]

🤘⚡️🤘

[@acservicetechchannel]

Thanks a lot Dave!!!

[@quantumgigavsigmaraven1745]

Woah

[@acservicetechchannel]

Thanks!

[@mynhauzenneyman2584]

🤔 добавь пожалуйста русский субтитры !

[@electrichaidar7841]

نتمنى منك ان يتم ترجمه جميع الفيديوهات إلى الغه العربيه

[@daulabot24]

Hi , you are a good teacher but you talking too fast . You have to slow down a little, in order to be more understanding .

[@MR-zf2di]

turn down the playback speed

[@ChrisKow-the-scientist]

You can always slow down the speed by going to settings!!! 👍🏾

[@MrRheo29]

I like this video , but he jumped on the scenarios too much. He should keep on track on one scenario at a time.

[@jandshatton331]

Could a piston stuck in heat mode position when running in air conditioning also produce low superheat and freeze the coil?