Lets see how a defrost circuit operates

Please consider subscribing to my channel and follow me below
Social Media
For any inquiries please contact me at

Subscribe to Channel:

This video by Curious HVAC Guy was liked: 551 times

If you like this video by Curious HVAC Guy, please support their CHANNEL by clicking on the SOURCE link below and Subscribe.



Featuring Your Videos:

By featuring your videos on our blog, your videos will receive hundreds of views daily from our website visitors, you get a backlink to your channel for followers to subscribe to your channel. This is a win/win for SEO for both of us. If you would like your videos or channel highlighted and premiered on our blog for FREE, please contact us.

However, if you no longer want us to premier your channel, and want us to remove your video and not feature your channel anymore, please contact us.

Video Post Disclaimer:

The information contained in the multimedia content (โ€œVideo Contentโ€) or post content in general, represents the views and opinions of the original creators of such Video Content or post, and does not necessarily represent the views or opinions of KASRefrigeration.com. The mere appearance of Video Content or the post on the Site does not constitute an endorsement by KASRefrigeration.com or its affiliates of such Video or Post Content.ย 

The Video Content or Post has been made available for informational and educational purposes only. KASRefrigeration.com does not make any representation or warranties with respect to the accuracy, applicability, fitness, or completeness of the Video or Post Content. KASRefrigeration.com does not warrant the performance, effectiveness or applicability of any sites listed or linked to in any Video Content or Post.

Affiliate Disclosure:

This post and description may also contain some affiliate links, which means that the post creator may receive a small commission at no extra cost to you if you click on some of the product links and decide to make a purchase. This channel 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

Copyright Issue:

If you find any of your copyrighted material in this post or video, please contact us, so we can resolve the issue.

All rights reserved by respective owners.

45 thoughts on “Defrost circuit in a commercial application

  1. Jacob Foxworth says:

    Really sweet rendition of a defrost circuit! I too live stuff like this. Great explanation of how it all works together. Keep up the great work. Also, I gotta say that I love your bumper sticker on the cabinet. I think you know the one. Up with dogs, down with cats. ๐Ÿ˜†๐Ÿ˜€

  2. DIY Garage Woodworks says:

    So where in the walk in freezer are the light bulbs at that indicate fan defrost and fan? Lol just kidding. Haha great video! Learned a lot! Iโ€™m in school now for hvac/r not sure if I want to go the route of residential or commercial. More I watch your videos tho the more Iโ€™m being swayed to commercial haha keep up the awesome work and thank you for taking the time to make these videos!

  3. throttle bottle says:

    you could wire the actual defrost termination switch in and use component "freeze spray" to make it cycle. not very cheap and you don't want to use a ton of it ๐Ÿ˜‰
    then again, just use and recovered R134a (as liquid through a nozzle) which is what "most" of those sprays are, I believe some are now R1234ze…

  4. throttle bottle says:

    a 3-way switch also seems like a good thing in place of the two. they're single pole double throw(SPDT). same function as the klixon switchng from one to the other ๐Ÿ™‚

  5. aus_aircon_ref_mech says:

    Great video. My question is when the defrost termination switch closes the switch on red to brown, does that also close the switch on 2-4 even if the timer is still in defrost? Iโ€™m a bit confused there.

  6. Jay Curtis says:

    Th8s is a great display. I wish I had something like that to show me the functions when I was starting out years ago. This should really help guys just starting out in the trade.

  7. W D says:

    I have asked a few guys to show how shit is wired up, and to explain it in detail. Anyone can change a bad part wire for wire. But understanding what your doing and why is golden. You did a fantastic job. You remind me of my father who passed away sometimes it's hard to watch your video's.

  8. Nunya Business says:

    Look at them crappy little relays to run the mega amps of a commercial freezer compared to the humongous contacts of an old fashioned mechanical timer, the best part is this thing has even been modernized and improved, IT COMES WITH AN OPERATORS MANUAL, choke choke !!! The modern philosophy, more bells and whistles, if it ainโ€™t broke, it will be soon ! Seriously though, nice vid bro, good show.

  9. Win Dennis says:

    I had to watch it 3 times but I think I have it now. Iโ€™m not in the trades but recently built in evaporator for a cold bay table. I added a 2nd condenser unit to the system. The problem is Iโ€™m using DC fans that run continuously and I have to manually defrost the additional coils. The original unit has shielded coils covered with stainless. Also I must thaw these manually. All that was background. My goal is to add a defrost cycle and heaters. I understand the wiring as you explained. The DC heaters has a AC inverter so I can rig a power outlet from the grasslin mimicking a fan delay. Still working that out. The answer is in your setup. Itโ€™s working on 120 Ac which makes it easier. Thanks for your video.

Leave a Reply

Your email address will not be published. Required fields are marked *