Heat Pump Defrost Thermostat Sensor DFT Testing!
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- čas přidán 17. 12. 2016
- In this HVAC Heat Pump Defrost Video, I go over the pivotal role that the DFT Defrost Limit Sensor has in making sure that defrost cycle happens so that the Heat Pump doesn't freeze solid in wintertime. I go over how to read the model number, what the letters and numbers mean in the model number, what the resistance values should be at certain temperatures, why the limit sensor doesn't open until it gets to the appropriate temp, and why it does not close until it gets down to the right temp. These are shown and discussed for a deeper understanding of how a heat pump and defrost board works in order to troubleshoot problems when they arise. Supervision is needed by a licensed HVAC Tech before doing this as Experience and Apprenticeship garners Wisdom and Safety.
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Information in this video is intended for educational purposes only. Any work related to the topics in this video should be performed by licensed technicians or by apprentices under the supervision of licensed technicians. AC Service Tech LLC is not responsible for any possible damages or injuries caused by the use or misuse of any information provided. ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
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I just found your videos, they are some of the best I've found. I have a lot to watch, but after the few I've seen, can't wait to watch the rest. Thanks
Thanks Brian!
Finally a great teacher these wackos at my trade school went on for weeks and weeks drove all of us students NUTZ. Thank you Sir
well I got to tell you that you are theeee best teacher I've seeing on CZcamsthank you for caring brother and hope you don't stop making these video
Thank you very much Teddy Acosta!
Another great video! Heatpumps can be tricky to work on. I have gained a lot of knowledge watching your videos.
Great to hear!
Thanks so much for the video brother, you saved me a ton of time and effort. I replaced the capacitor in my unit because the condenser fan would not come on, i tested the fan motor and it tested out fine, i was beside myself wondering what i was over looking. As it turns out, i just happened to be out back when the condenser only was running and the fan not running because it was in defrost. I thought "omg the compressor is going to burn up" not even thinking that it was designed to do that on a heat pump. I was thinking in "summer cooling mode and its 115 outside" in my head, not its 37 degrees outside tonight in AZ. So i shut it down and have been trying to figure out what was wrong with it for two days now. The defrost switch was stuck in the closed position and never got a chance to open until i shoved a heater down inside and heated it to 80 degrees, then i heard the "click" and knew I was an idiot. Thanks again brother, you saved me the price of a fan motor and many head aches lol. Wife just looking at me shaking her head now, and i can't blame her one bit, hahaha
Nice seeing these components so close up and explained so clearly! Thank!
Thanks a lot Jack!
God bless you brother for all the efforts you putting in and the knowledge you sharing . Great video
Thanks Mohamed!
Thank you for all your showings....
Thanks eman3208!
Thank you for doing a nice job on showing everyone thing like this.👌👍
Thanks Lance!
another excellent video!!! man I am very inspired by you thank you for sharing hope to see more happy holiday's partner!!!!!
Thank you very much and have a great Christmas jimbola77!
Thank you very much! I'm just a diy guy and happened to notice my condensing unit freezing over and apparently not going into defrost mode last night. I was able to disconnect the outdoor fan and jumper r to o and force defrost. That melted all of the ice in about 5 min or so and I also changed the accumulated timer pin on the df board from 90 to 30 (not sure if that will help) however I did notice a sensor that was just hanging and not attached to anything last night and didn't know what it was. I assumed it was normal. I don't know if it is indeed the problem or not but I'm anxiously awaiting getting off work to test that hanging sensor. That I now believe is the defrost sensor (thanks to you) I have followed your channel for awhile now and have learned quite a bit, I think you do a great job at explaining things and just wanted to say thanks! In a really long way apparently lol if by chance you read this and have time could you let me know if I'm heading in the right direction....just need to figure out where to mount the thing I suppose? Thanks again have a good weekend.
Glad to hear the video helped. The dft is mounted on 3/8" tube attached to the outdoor coil as close as you can get it to the coil. How did you make out?
acservicetech not sure how it came off but that was definitely it. Thanks again, now I need to figure out why my 60 amp fuses to the inside air handler are blowing? Changed one fuse twice in 3 weeks. I have been using emergency heat in the last few weeks because it's been around 20 degrees or colder in Maryland. Was told that I may have a issue with one of my electric strip heaters. Everything is working great at the moment, I think I'm going to leave it be for now and hope it was just a fluke lol ....that's never the case though, thanks again bud , I owe you one
The best school ever. Thank you much
Thanks moeselec, if you want send your email over to info@acservicetech.com and I will send you an email once the procedure book is published, thanks
Thanks for the video! I have an old Carrier heat pump, and the sensor seems to be an NTC. It doesn't have any info on it, can't even search for a replacement. What do you think, can I replace it with a simple on/off clixon sensor? Thank you!
Great video thanks a lot sr!
Was having this exact problem because dft was faulty it was causing my 3amp fuse to trip thanks alot brother for the advice
Thanks Big Mari!
Thanks, great.
Yes it would be nice to see how to change an oil in the compressor, thank you!!!
Thanks for letting me know jimmy!
where is the best location for the sensor? i have one that keeps freezing up. the sensor was on one of the distribution tubes from the orifice. im going to put it on the coil tube.
Could this cause it to instantly start freezing on the inside and outside unit
Or does that sound more like low pressure?
Hello :)
Heating on my unit works. In cooling defrost gets triggered quick. Sometimes after 30minutes. sometimes after 5... What sensors can call for defrost mode ? I ohmed good OAT and OCT
Thanks!
I'm checking my defrost sensor, thanks to your videos. I'm wondering about the dense black material around the sensor. Is it insulation or just securing the sensor in place? Thanks!
It is actually both, thanks
Hello acservicetech do you think you can make a video in how to change an oil in a compressor...thank you!!!
No promises, but I do want to know what everyone wants to see. It helps me as I have time and as I run into or get a piece of equipment. Thanks Pedro!
If the switch closes at 30F to activate the defrost then does that mean the heat pump will only run to temperatures above 30F since the coil has to be colder than the outdoor temp to collect heat?
No, once it's reaches 30F or below the heatpump keeps going but a timer starts for 30 or 90 min. Then the defrost starts and goes till the coil reaches 80F. Then back to normal. That's my understanding anyway
Where is the defrost temperature sensor located at the very bottom of the coil?
So if it’s closed is frozen and if it is open is melted or defrosted
I have a few units where the AC will only work when the red low voltage line is disconnected. Any advice?
I would need to know the make and what it is? Are you talking no 24v power to the defrost control board? If that is the case then there is no way it would suck in the contactor other than if the contactor contact is melted in the closed position.
acservicetech It’s a Goodman. (Don’t know exact model without looking at it). And whenever I disconnect the Red low voltage line from the Defrost Control Board the unit will turn on but when I reconnect it it turns off.
did anyone go in and mess with the wiring. It almost sounds like a power wire is on a normally closed side when it should be on a normally open side of a relay. Is there another 24v power source for the unit that it is using as well?
Is it common to come across defrost thermostats that are bad?
It is not that common but it is good to know how each component works in order to determine the defrost problem. Did you check out the "acservicetech defrost playlist"?