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

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Thank God someone who finally talks about the problem

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.

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

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."

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

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

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

As always I appreciate the video, very educational.

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

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

ALWAYS AWESOME ADVICE GREAT JOB CRAIG

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. 👍🙏

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

Great job as always sir!👍😁

Thanks for all the videos

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.

awesome!!!! thank you for sharing.

As always nice videos

You are just amazing

Great video!

Thank you for sharing very nice

Awesome video!

Thanks for the info dude.. Awesome..

love the video

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

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Thanks!

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

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 :):):)

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?

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

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"

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.

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.

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

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?

🤘⚡️🤘

Would really enjoy a video on variable frequency drives.

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.

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

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?

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

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

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.

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

R4-Tenay

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?

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?

Woah

can u make another video with 134 pls?

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!!

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.

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?

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.

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?

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.

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

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.

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

what if negitive subcool?

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%.

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

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.

Also, thermostat set a too low for desired temperature!

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

Do you have this book in Spanish?

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

Why am I still up¿

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

🤔 добавь пожалуйста русский субтитры !

نتمنى منك ان يتم ترجمه جميع الفيديوهات إلى الغه العربيه

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

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