This video will help you diagnose and troubleshoot low voltage issues you may be having with your thermostat (red wire) using your multimeter... as well as fixing the issue!
Your tutorial was spot on for my LV short circuit. Nobody else covered this procedure like you did in detail. They say do this do that, but do not explain what is happening. Your are a very good HVAC teacher. Thank you!
Just wanted to drop in and say ty so much for your videos. I'm financially hard up and hiring a professional just wasn't in the books. We either had to figure it out or learn to live without. Your information clearly and plainly helped me understand how to diagnose and solve. I feel like I owe you more than you've given me. My family is grateful for your educational videos. Ty and God bless!
I am installing a new thermostat and things I read online suggested a I blew a fuse, but didn't really help me with where to look. This is very helpful. Thank you!
One of the best videos for informational purposes. Describes the process and parts but doesn't go off on confusing rants. I'd use this as a training video for new techs because no matter what system is in place this process is going to be essentially the same whatever you're working on. Thanks!
It's also important to address how the fuse blew. I would check the 24v coil on the contactor at the condenser and read the resistance. These coils can start going bad and take 3 amp fuses out and cause frustrating call backs.
If the fuse is blowing that means it’s doing it’s job. I would be looking for shorted low voltage wires primarily and faulty components such as a contactor, control board, loose wires, grounded wires, etc.
I watched several videos and this one walked me through like I was an idiot. I am an idiot when it comes to a/c. The step by step instructions were easy to understand and follow. My central air works again and I saved easily $400. Well done sir.
You fixed your AC? You are no idiot! The goal is to explain things step by step while being as thorough as possible. The reason I do my videos in this format is because like you I used to watch video after video and still was unsure of what to do. I decided that if I ever started a channel I would teach in a way that anyone could follow the steps and be able to troubleshoot. Great job fixing your AC! 🙂
if you've got a popped fuse, it's because of a low voltage short. before replacing a fuse, you need to find where that short is. if not, you are going to have to replace that fuse once again.
Yup just gona say this where is the root of the problem...can u detail where u start to look for problem in low volts area donu start at sequence of ops not sure ?
I agree; however sometimes especially in Florida, thunderstorms will cause power surges and cause multiple problems with circuits. I have lost fan motors, circuit boards and transformers due to electrical surges. I installed a power surge strip and it solved the issues
Dude you are a stud! Thank you!! I know my stuff when it comes to electrical with 25 years experience. Today my detached garage AC stopped working. I checked the voltage at the thermostat. No voltage. I pushed the coil on the GP contactor. Worked! Next stop is the rafters to the control panel. Thanks for your help.
Thank you very much for this video! It helped me diagnose my AC issue and got it back running and blowing cold air. My wife and kids think I'm some sort of superhero now...
Great walkthrough with clear and detailed steps. I was replacing thermostats and blew the fuse. You saved me $$$ with this video. Good Karma coming your way my friend. Thank you!
Great video; thorough and logical. The 3 amp fuse on the air handler circuit board was indeed the problem. I would have had to pay $200 for an emergency service visit, if not for this video. Instead, I spent $5 at Ace Hardware and -- problem solved! Thanks so much!!
You saved me hundreds of dollars! I relocated my nest thermostat and accidentally connected the wires without knowing the consequences. After watching your video, I fixed it with a $2 fuse!!! Thank you!
You rock Sam. Loved the way you logically walked through the steps... it all made sense to me and I was able to pin down my issue also (mine was on the transformer)
Just followed your steps exactly and this fixed my issues at 5am. Wife got up with the baby and noticed it was 76 degrees in the house and I had the issue fixed within an hour. Can’t tell you how thankful I am for your video.
Great video! I just started my HVAC career and I’ve been doing a lot of service no AC calls. These type of videos are definitely helping me out with trouble-shooting issues. Thanks brother👍🏻
FYI, if it turns out you have 24 volts in the air handler, but not at the thermostat, check the overflow sensor (safety switch)to see if it's keeping the unit from turning on. Thank you so much for this video!
Great video. I had the same issue. I installed a new Honeywell thermostat without looking at the directions. Long story short, I had two wires, O and B connected when I just should have had O. For whatever reason that shorted the control power on the heat setting only (not cooling) and blew the control power fuse. Today was one of those learning days. Thanks Sam!
Thank you for very detailed and thorough video. I had already working through the steps confirming no power at the thermostat but didn’t know where to go from there. I had the same fuse issue. It got my ac up and running and made the wife happy. Thank you!
Sam: THANK YOU! This explains a lot. I will check tomorrow morning whether I have the similar board and a fuse that I can replace. This afternoon, while trying to be a smartass I may have blew that power. My problem was a that the CAP was out. I did replace the cap first. The contactor relay was kicked but the FAN and the compressor was not running in while the bad cap was there. By the time I procured an appropriate CAP and replaced it, the thermostat (which I have a NEST), may have stopped calling for cool. While working outside, I looked around for other reasons why the compressor did not start. I found this little fixed thermostat-looking "Crankcase Heater Kit" that was terminated between L1 and T1. Thinking that it needed to be normally closed, after measuring it open using my Multi-meter, I cut that out and bypassed it by shorting the two leads that went to it. That must have done it! Killed the Low voltage power fuse due to the flow of unusual current through the circuit. After that, when I pressed the contactor in with a screw-driver, the fan and compressor ran fine (with the new CAP). But it will not run under the thermostatic control. Playing with my NEST Thermostat, found that it was complaining about Power and was showing an error code "e-23". Called Nest support, they were somewhat knowledgeable on the troubleshooting of their Nest product, but not enough to tell me what could be wrong with the Air-handler side control Unit that supplied the low voltage power. Your Video was quite helpful and makes sense, that the fuse may have blown in the control board. However, my model Carrier, may have a different control module. I will have to search for the fuse location if it is in a different location. I will let you know what I find tomorrow. Again thanks. Great Video and you earned a subscriber!
Had a no a/c power showing on thermostat, checked all the initial things like circuit breakers, both disconnects on air handler and condenser. Checked the buss fuses. Started searching here for more in depth diagnosis. Found your video, followed the methodical step by step procedures. Turns out it was the fuse in the air handlers circuit board. Replaced and back up and running. Thank you for an easy to follow approach to figuring this out.
Good video. I do commercial bar concession stand refrigeration at work but have never opened a typical residential split a/c system until recently. Went to change out a worn contactor and capacitor on a dirty but functional system. Cleaned the condenser coil, ready to restart the unit thinking I'm gonna cash in some hero points on this friends and family trade... plug the disconnect back in and....... nothing. Huh? Took a while to figure out that even though I pulled the outside unit disconnect that I had shorted out the low voltage while changing the contactor. Live & learn every day. Thanks for sharing.
Great! Sometimes it's a simple issue that is overlooked. I have to always remind myself of this in the field. It's easy to overthink and expect the worst... when it may simply be a fuse! Thank you for the feedback! Great job on the work you completed.
6:05 ! Replaced the capacitor, Start capacitor, Start relay, and contactor…still no power to fan. Found the #5 fuse in my unit in the attic BLOWN. Cheapest replacement part and that’s what got me back up and running 💨. Thanks Sam you the man !
Wow this seems to be exactly what I'm facing right now. I have no power to my 24v wire at my thermostat. I need to test the other things you mentioned now. Also there is a bag of fuses on my unit upstairs from a technician when he was here last. Thanks!
Thanks! I was trying to connect my 24V return so I could use a wireless thermostat. Must have blown that fuse. Not only is it fixed, but the wifi thermostat is working like a champ. Thanks!
Guess who changed thermostat with out cutting off the main board 😩 this guy. U saved me a few hundred. Thank God for space heaters. I’ll buy the fuse in the. A. M. Great video
Thank you for your instruction, my AC systems have same problem, my thermostat voltage measured 2.4 VAC. I followed your instruction and found the fuse in the blower unit which located on the attic. My AC back up and running after i replaced the fuse. Now the thermostat voltage measured 28.5 VAC.
Your video got me up and running! I blew the fuse when I changed a thermostat ( rookie mistake ) thanks for bailing me out so I can sleep tonight in a cool house instead of a hotbox....thanks again
Just wanted to echo what others have said previously. After I installed a new thermostat, it didn't power on. I found your video after asking Doctor Google for help. Thank you for the thorough and clear explanation. I traced the problem to the fuse in the air handler. Replaced the fuse and everything worked.
Just wanted to say thank you. I now know how to properly diagnose with just a multimeter instead of trying to replace parts. It happened to be the fuse on the unit I was working on.
Great video, organized and to the point. My problem is solved. Nice to see a video that is intelligent and a great educational process of elimination through testing and moving on to next component to examine/test.
Legit just saved me! My ac went out mid day yesterday and then today bought a new thermostat and nothing! Then worked my way to the 3A 32V Fuad and BAM it was blown. Purchased a pack of 5 for $6 after taxes. THANK YOU
Well you just saved me at least $100. Had low voltage on my tstat (must have shorted when installing my nest), checked out the things in your video and swapped the 3 amp fuse. Works fine now. Thanks man!
I was pulling what little of hair i had left out!! BTW not good for a strugglin hair farmer 😆😉 AWESOME video describing step by step to chase and troubleshoot the REAL issue.....board fuse!! Thanks* So very much for this video!! 💖
Great tutorial. I bought a house here in Vegas and there were wires coming from 1 Furnace to another. I checked because i upgraded to a smart thermostat and needed to connect the C wire. I suspect the transformer is busted because i checked the same purple fuse and it was ok, but the red board light was not blinking while pressing the black safety switch.
BRO! BRO! BROOOOO!!! You saved me and my family from turning into rotisserie chickens! Thank you so much! This was definitely my problem and you helped me fix it! 👍👍👍👍
This video saved me!! Just crawled out the attic to write this. It definitely was the fuse. Wierd that my compressor wouldn't turn on but my motor in the attick would run automatically even without the thermostat attached. Stuck relay maybe? Regardless I now have cool air.😊
Thank you bro! I think I Found my problem using your steps. My transformer was not sending out 24v. Ordered the transformer and hopefully fix my hvac! I'll check back in in 2 days
David Figueroa I just fixed mine about .5 hour ago! I’m glad these videos are available! Otherwise I wonder how much we would’ve paid if we called someone. Thanks!
update : without doing anything the ac started. I do have the 24v back at the thermostat. While it is a good news, there is trouble as well. I was not able to "fix it", it just fixed itself, which we all know isn't exactly a fix. So I suspect control board contact issue. I already have the same problem with the gas heater, often works, sometimes not and I narrowed it to control board issue. I might have to buy both control boards. Anyway still the video helped me and was awesome so thank you !
Thanks a lot. I feel so dumb. After I installed my new thermostat after the old one died, the out door unit still didn't work. So I just replaced the capacitor even though I already replaced it 3 years ago. Still nothing. I bought a voltage meter and checked the contactor and it received 240v. When you showed the thermostat wiring I decided to check my wiring. Yup. The wrong wire was in the wrong port. I had the white wire in the White port. It supposed to be in the Yellow port. Fixed. I was worried I had to go up into my attic.
My magnetic switch inside the a.c. broke it's contact conductor holder piece. It's plastic and holds the part that moves down to contact the contacts thus activating the capacitor..
