How To Replace a Fuse on a Furnace or AC Air Handler Control Board

[@butchberardesco5508]

You are the MAN!!!! My AC would not turn on.. it reached 90 Degrees in my home. After much testing, I found the 3 AMP fuse was blown. I googled the 3 AMP fuse and your video came up, and your very informative site walked me through why it blew. I had bare wires outside next to the air handler. I repaired the wires, replaced the fuse and my AC was FIXED... I cost me $5, and I have 3 extra fuses!!! Thank you for sharing your expertise!!!!

[@jermainehenry7180]

Thank you! Was starting to panic when my heat went out on my heat pump system. Checked the fuse like you said and yep, it had blown. Quick trip to Lowe’s and now she’s back up and running! Thank you.

[@Jeckyli]

I watched a dozen videos today as I accidentally blew the fuse while replacing thermostat. This is the best video out there. Not only it helped me to fix the problem, saved me $80 for getting someone onsite, but also this helps me clearly understanding almost everything on the board. Thanks a lot for doing this video!

[@rubensanchez9760]

Same here

[@atltai]

Exactly why I watched this video lol

[@rllewis]

Ditto!

[@mofassy]

I keep blowing the fuse while replacing the thermostat Could you help me Thanks

[@KHAOE1]

@@mofassy did you ever find out what the problem was? Mine is doing the same thing.

[@griffinhowell8374]

Thank you so much! I was just refunded a $75 service fee after watching this video and replacing my furnace fuse myself. Thermostat came right back on and everything is working smoothly again. Subscribed!

[@kc7136]

you saved me tons of money. I shorted the fuse when I was installing the Nest Thermostat!! thanks a million

[@erickuehne1767]

We’re you still able to install the Nest? I didn’t realize my wires weren’t solid core and must have accidentally shorted while I was fiddling with the wires.

[@laurentl2603]

This video on blow fuse showing the code on the furnace door panel saved me call for a real easy fix. Thanks!!!

[@christinaheikkila5721]

YOU ARE AMAZING! We haven't had any heat for several days due to a bad thermostat. In the process of replacing it, we somehow blew that furnace fuse. Took a couple hours to figure that one out! But after watching your video, you saved me $$ and from going insane! Thanks for so clearly explaining "how" and the "why" in your videos. I'm a fan!!

[@toddbaker4264]

Thank you for this video. Just saved me a service call. I forgot to turn off the breaker before switching thermostats. New Nest thermo and NOTHING! Numerous videos and research and then found this one. Completely forgot about the fuse. Thank you!!!!

[@mfvarnum58]

Thank you for video. Saved me $75 service fee by diagnosing this problem.. my thermostat was not getting power and this help me figure out why.. burnt fuse. im replacing it with a 5amp automative fuse. 3 amp will work too.

[@damongwinn]

Outstanding video!! I blew the fuse changing out a thermostat on a hot Saturday in Houston. You saved me hundreds!! Thanks a lot!!

[@huynh9883]

Thank you so much Benjamin. I was complaining to the Nest thermostat representative telling I need a technician coming out to solve the issue. looking at your video explained why.

[@SunnyPatelFromHuntsville]

This is great video. I was able to fix this by changing the fuse. My HVAC unit wasn't powering on since the fuse was blown. Thank you Benjamin for great video.

[@davereitzel9528]

Just watched video. My control board doesn’t have replaceable fuse but there is a reset between two wire that connect to firebox. That did the trick. Thanks for posting as it helped me troubleshoot.

[@ElCapitan1718]

Mr Sahlstrom, another great video. I recently had to replace the 3-1/2 amp slo-blow fuse in my mini-split heat pump unit. My unit uses the 5 mm glass cartridge fuse. I had to order a replacement online. The fuse in your furnace is easier to remove/replace, and I believe is available in auto parts stores. I appreciate your work, and I find your topics interesting and informative. I hope you and your family are safe and in good health.

[@derrickbray]

P

[@Gmoon917]

This guy knows what he’s doing GOD BLESS YOU BRO

[@ZaoHuZhua]

Thank you! Snipped my wires while remodeling to move my thermostat to the adjacent wall figured it’s low voltage and wouldn’t cause an issue. Glad you provided a detailed and clear video to fix it. Saved me calling an HVAC technician out!

[@PunjabiMediaJunction]

Thank you very much for helping me figure out that I had blown the fuse while changing my thermostat. I almost called someone to fix and would’ve cost me a lot of money.

[@GetGetMoney33]

Thank you sooo much for this video. You have no idea how many videos I watched did not touch on this point. I would've paid 200 dollars to fix this issue when it only cost me 4.98 for the part to fix it.

[@courtneyburns4006]

Thank you for this video!!!! Just installed a smart thermostat and this helped me identify the blown fuse as the source. Also learned some new things about my furnace.

[@PF_Health]

Thanks for clarifying the "3" amps that I thought was wondering what "E" meant. Trying to change my thermostat to a Nest accidentally touched wires.

[@christophercianci5842]

Dude you rock - my exact issue with shorting out the fuse when i went to change a thermostat ....THANKS!

[@migosmadeira9892]

What if your air handler doesn’t have a circuit board? Mine is 1977 Bryant. I don’t see a 3 amp fuse also . I was messing with the thermosthat , I bypass it . I was trying to fix a no start heater I short circuited something in the proccess and now the AC doesn’t turn on also. Any tip what to check? I don’t see any fuse or circuit board. Could it have killed the transformer?

[@nafowler]

Simple and good explanation about why this happens. Describes my scenario exactly so hope it works for me

[@kamran66]

Nice and simple to understand video.....thanks! I like the fact you showed us exactly which wires will blow that fuse

[@psfgtech]

My ac is opposite, and my 3 amp fuse is in a mix of wires. My thermostat is out. I should had gone to AutoZone and grabbed a replacement, because AC repair guy only had a 5 amp fuse, that made my thermostat blink and not come on- Great extra information as well, thank you

[@mollygalbreath1667]

YOOOO thank you so much!! Straightforward, simple, to the point. I fixed my furnace without calling my landlord!

[@jackfrank303]

Good info. Going to look for that fuse next time I have my furnace open. Thanks.

[@24tupac]

Thank you so much for making this video you saved me 8k that the technician was trying to charge me for a while unit. I replaced the fuse and everything is back and running fine.

[@teenhcl]

Thank you so much for the on point lesson. I learned the lesson that this fuse can blow if you don't cut the power before replacing your thermostat - the C and Rh wires may touch each other before you know it.

[@TonyaRocks]

Thank you so much, just found out today I had covid, get home and my heater doesn't work, I was looking around and had pulled the fuse and it started up running the blower, just like in your video, unfortunately the hardware store closed 3 minutes prior to my pulling the fuse. Also it is unfortunate that I had to watch so many other videos to get to yours and confirm what I was thinking

[@andydahlstrom6041]

This video saved me probably $300. Thank you, everything you described here worked like a charm!

[@boorayin2773]

Your video was actually super useful and I was able to see everything that you said I might see per your instruction. Bad news is that my fuse was fine...am going to try changing the capacitor next. Good step?

[@boorayin2773]

It was a bad capacitor - I know how to check my fuse now, though. Thx! :)

[@alexquiton7279]

Thank you so much for helping others 😊you just save me a lot of money 💰

[@BenjaminSahlstrom]

Happy to help!

[@dandicaprio4703]

Dude, you just saved me $200....THANK YOU WITH ALL MY HEART

[@jonsmith-p7n]

Thank you in advance. I'm trying this before a new fan motor. Already replaced the capacitor

[@Joe-qw6il]

Another great video Ben, a while back I went to a smart thermostat and had to use that extra wire, lucky for me it was neatly tucked behind the wall, I did however have to go up into my attic to connect that extra wire into my air handler control board, this issue might trip up some of our subscribers-- maybe a quick video to show people how to do this--otherwise great content as always!

[@IIIllllIIIIlllll]

Whats the general process to do this? Mine has an extra blue wire but guessing it's not connected to the board. How/where should that connect to the control board?

[@ilkobe8787]

Thank you for your detailed tutorial. Fix my AC for less than a buck!

[@michaelwalling8281]

Another excellent video Ben! You have a real talent for instructing. I listen to your videos at normal speed (Meant as a complement). Also: I am having a hard time believing they made the blue common when they had a green and a white available. What was the thinking behind that?

[@tyleredmunds2948]

you legit just saved me 400 bucks. great video and thank you!!!

[@darrenstensland5301]

Thank you so much!! Actually showing the blown fuse was key for me.

[@georgeian3243]

Dare I say it, if you can’t find a fuse and it’s necessary to get the furnace going, you could jumper the fuse holder terminals and restore power to the board. However, as Ben said, you must be certain the cause of the fuse blowing has been found and repaired, otherwise restoring power with a dead short will cause the “magic smoke” to escape from the board. It’ll be completely ruined and wow, are those boards ever expensive. When in doubt, don’t jumper out.

[@jimenezalma18]

This is definitely the best video out there. Although I got lost where he explains why it burns out. My unit was recently replaced and in fact the wires were pulled out of the wall and relocated. I didn't understand that part 😭😭

[@davidh109]

Big help, this was my issue, and it's 90 degrees upstairs. Thanks.

[@BarryBryant]

Saved me an expensive weekend service call. Thanks!!!

[@ThatFixItGuy]

Great information. Thank you for walking through all the troubleshooting steps of that fuse.

[@checopacheco420]

Muchas gracias amigo tu siempre con muy buena información técnica thanks my friend for your technical support.

[@drodjr20]

Wow you literally explained exactly what I mistakenly did with touching the two wires and blowing the fuse. Thanks for helping me find the problem.

[@johnreeves3380]

Ben, thanks man. Another great helpful and well edited video. Thanks for keeping it to the point, every time. Appreciate you down here in Carolina

[@michaelwalling8281]

Carolina? He has a definite Northwest accent. People move around so much these days, many people from the south don't have that twang anymore.

[@JeffWolfram00]

Thanks so much. You saved me a few hundred dollars on a service call where he would have just changed a fuse!

[@shanerodgers8033]

Wow, so helpful and straight forward info! Thanks so much!

[@larryotoole933]

Hey Ben another great video 😀 I can save myself some money repairing my heat and ac thanks

[@smokeshowingfitness]

Very helpful and informative. Very direct and clear when explaining.

[@rainrain9018]

Thanks. This video saved me at least $100.

[@tillercorp]

You just saved me $300. Thank you

[@klr650hubbard]

I love u. Thank you. I went from feeling like the worst pos to cloud 9

[@DrPogosyan]

Excellent. Thank you for helping me saving $$$ with you video

[@qblinden21]

Thank you! House is warm again.

[@arelyhernandez6788]

Hi, so a quick question, what can be wrong if that fuse keeps burning

[@Amy-gi8ej]

This is such a fabulous video. By the best. Keep up these videos!

[@Charlie-phlezk]

@0:30 man, you had me thinking I needed glasses, I swore that was an E not a 3, lol. All the dyslexic viewers thought it was their mistake 😅

[@johnschumacher678]

This video saved my life

[@rllewis]

Thank you! Saved me hundreds in house call.

[@vgordon4203]

Exactly what happened to us…thx,you saved us $$$$!

[@Casper_Espresso]

It looks like you diagnosed exactly why I blew the fuse. And this makes me put it back together properly. First turn the power breaker off. Second install the new thermostat. Third install the fuse. Turn everything back on and hope to God that everything is going to work. But I'm pretty damn sure I blew it by shorting out the common

[@CBRmike83]

TY….replaced therm and powered off wrong beaker hooked up new therm nothing worked but my fan was just on high noticed a burn in the fuse and did not know these are just auto type fuses. Replaced with one from Ace and boom fixed A tech wanted 450$ to fix it said some wires and board was shot well 5$ fixed it TY

[@BenjaminSahlstrom]

Awesome!

[@silviacovic1494]

Thank you so mutch, very useful. I saved 400$

[@tri-eye5554]

Thank you for the video ! Saved us some money ❤

[@MrVelez809]

Hey do I have to have the thermostat disconnect with all wire separate to replace the fuse ? ?? Thanks

[@freddiesims1006]

Wonderful stuff! Thank you Benjamin. We appreciate you.

[@hmurchison8123]

I’m a ten percenter. Subbed. Thanks Ben.

[@mrbreezeet1]

Just in general if you had a fuse that kept blowing I know I do it in automotive and on my motorcycle but can't you put a light in between where the fuse goes and as long as you're short is still present the light will glow brightly and when the short is eliminated, the test bulb will just glow dimly or go out? Of course you would need a 24 volt bulb I don't know if it would burn a 12 volt bulb out if it had a direct short it probably would.

[@Handlehandlebars]

So maybe I missed it but was the cause of your blown fuse sombody shorting out your power wire when they moved the thermostat?

[@radiohead6283]

Great video. Super informative.

[@jaskosabina]

Thanks for the tutorial it worked !

[@siroossoleimanian4813]

It was great explanation. 👍

[@MP-zf7kg]

ugh. really wish these things would use circuit breakers. He's totally right, it takes next to nothing to short out a wire....and of course you'll do it on a really cold or really hot day.

[@mike12345807]

You are the man! Thanks

[@SaturdayMonk]

Saved me a couple of 100 bucks... thank you!

[@ahadu02]

We really appreciate your information .Its a big help GB.

[@joseakajcp]

Hey Ben great video, so at 6:17 you said you need to close the door for it to get power?

[@tarawadsworth8216]

You saved us! Thank you so much for this video.

[@gusc6785]

What about the on/off dedicated circuit switch thats supposed to be in the area usually attached to the furnace?.

[@BenjaminSahlstrom]

They are not always present as if the furnace is in the same room as the breaker panel it is not required to have a separate switch. You're right though, usually there would be a switch on the side of the equipment.

[@gusc6785]

@@BenjaminSahlstrom ohh , i thought it was a requirement. But yes ive seen where there is none

[@Handlehandlebars]

So my brother's dosnt have a red light just a green status light...also there seems to just be a manual rocker switch on side of panel. When I turn that switch on I just hear a loud humming from the panel ...could his blower motor be bad?

[@98r648]

Great video! Thank you!

[@dheerajagarwal7957]

Thanks for the video. My furnace was dead due to fuse blown away. I was changing thermostat without turning off power. So red and blue must have touched. Now the fuse has been replaced, I can run furnace by door's switch. I am see one flash - system lockout. What needs to be done to fix this ? Any help is appreciated.

[@adampenrose9286]

I contributed some $ to your channel, and hope others do to. Thank you, thank you! Very helpful!

[@mbmass]

Just wondering, could the fuse have blown because the compressor froze up due to a clogged filter? I replaced filter and let compressor thaw completely but when I turned the system back on the air handler would not turn back on.

[@nicoleconner5404]

Super helpful. Thank you for the great video!

[@porelmofle]

Thank you man!!!! Love you brother for this amazing help!!

[@R357R]

Can the fuse blow if your batteries at the thermostat go bad?

[@headsail]

Awesome video, thanks!

[@twocents7495]

I really appreciate this video. ❤

[@MysticMountainNebula]

If I’m not seeing any obvious shorts, can this just blow from overuse?

[@micah9676]

What it can blow from is a clogged filter. Which will blow the fuse and shut down the system to prevent damage. A clogged filter is a common problem for blown fuses.

[@davidmckinney6577]

Hello Benjamin 👋 good video buddy 👍...

[@chocolatemilk2076]

Fixed my problem 💋

[@jenh8854]

Is it possible my Trane AC condenser/handler does not have a fuse? I have two zones and the upstairs unit 2 just stopped working recently. I replaced the thermostat-no luck. I replaced the capacitor-no luck. Then I got the brilliant idea of switching the good contactor from unit 1 with what I suspected was a bad one on unit 2 and sure enough, the functional AC unit stopped working. Problem is, putting the good contactor on the unit 2 did not make it run. Now I have two dead AC units!!Fairly certain I blew ‘something’ but I see no fuse of any kind in the condenser. Help!

[@tarahardy26]

I have a Rheem and took off my panel and there’s no fuses insight. Any advice

[@TUANVU-k4c]

good job, thanks you so much!

[@Goodtimesgoodvibee]

Hey Ben, I replaced the fuse, it turned the the system back on, but the heat & A/C are not turning on - but there is air flowing. Also, the thermostat seems to be going on and off. Any suggestions?

[@frankSANDIEGO]

Hi Ben, my 3 amp fuse keeps popping when I turn on the heater but it stays on if I just turn on the fan. An Electrician told me to switch out the white wire on the thermostat to the brown then go to the furnace and do the same. What is your opinion?

[@rameezrazzak]

Dude, I should pay you!