Why does the gas furnace short cycle 

Thanks so much for the advice! I was having a 2-3min short cycle. I found the trap off the inducer motor totally plugged up. I cleaned it out and blew out all the vacuum lines and I was back to normal!

YOur a life saver wake up at 3am to a freezing house and spent 2 hours trying to get the heat on and nothing worked than as i gave up i watched this video and said fuck it and tryed it out cleaned the stick and boom works 100% now and im all warmed up thanks again man LIFE SAVER you are

Perfect. I had this problem for about 4 months and when the wife finally spazzed out about it and threatened to call a service co, I looked at this video and realized very quickly it was a dirty flame sensor. At the same time I removed and gently cleaned the ignitor rod. Put it all back together and it fired right up. 10 minutes of effort saved me a bunch of money and put me back in good graces with the wife. AWESOME!!!

Cold night in Oklahoma tonight, 1am and we were freezing in our home 57degrees and getting colder. Figured out furnace was not staying lot longer than few seconds, googled it and found this video. Thanks to you we are not cold in our home any longer. Cleaned the flame rod and no more short cycle. Thank you so much for the video, you rock!

Dirty flame sensor, exactly as you described. A few rubs with steel wool and the heat's back on (It's 18 degrees outside). Saved me a service call and a day off work. THANKS!!!!!!!!

This video helped me immensely when I thought my furnace had a short cycle problem. I did the basics like change my air filter and thermostat batteries, still short cycling. After watching this video, I decided to open the front panel of my furnace to check what was happening. I then realized that the furnace operation must have jostled loose the screws that keep the safety switch pushed in with the panel. After this, i was so relieved to not have to call for maintenance! Thank you very much!!

You rock dude. 10 pm. Short cycling furnace. I cleaned the flame rod first, just like you suggested. I'll have a 'Clean n check' done this week just to be sure.

I'd been experiencing issues with my furnace short cycling since we purchased our house in Dec. Found your video, took the suggested steps and have not had a problem since.... Thank you so much for your expertise. Excellent video!

Great tip! I took out the flame sensor rod cleaned it with a brillo pad and now it's working beautifully! Thanks for posting this video!

Thank you so much for this topic! Our Coleman Evcon furnace has been giving us problems for a couple of years. I watched your video a couple of times and then cleaned the flame rod with some 400 wet or dry sandpaper. It stayed lit for about 5 minutes then went out with a "limit switch open" code. Then it ignited again and is still working! I especially appreciate what you said about the pressure switch not always being the culprit. Your photography is great.

I just saved $ 250 , because of this post. Thanks

You nailed it. We have small children, came home late one -13 degree night to find house 60 degrees. Thanks to your video we now have heat. We had snow drifts over both the intake and exhaust. Thank you so much for the advice.

Thanks for the excellent video. it allowed me to get my furnace running normal again.

Just wanted to send a note of thanks. My furnace stopped working this afternoon and my wife and I (and our three young daughters) came home to a cold house two nights before Xmas. We were thinking we would have to call in an emergency technician and shell out some major cash. Instead, armed with a little bit of knowledge and your video, I was easily able to fix the issue myself. Thank you SO MUCh for the video. You’ve saved my family from a cold Christmas.

Thanks so much! I tried cleaning the sensors to no avail like every other video says. But when you mentioned the air filter I check it, and it was filthy! The thing was choking for air.

I tried cleaning the flame sensor rod multiple times with no luck, but one of the drain pipes for clogged. I removed the pipe clean/flushed it with hot water and reinstalled it. Furnace working normal again! thank you so much for informative visual.

Knowledge is POWER! Thanks man!

Great advice! I woke up this morning to 9 degree weather outside and 55 degrees in the house. My furnace was igniting, staying on for less than a minute then turning off. The video gave me clear instructions and in less than an hour I'd identified a clogged drain, unstopped it and got my furnace back in service. Thanks

hey dude! this is very informative for a novice like me... now am beginning to understand how the furnace works.... thanks

Your video just saved me money I didn't have! I replaced the inducer blower motor 3 years ago. I didn't think it would have a little water trapped in it. Thank you so much

Thanks for your tutorial video I fixed the problem thank you again

My gas furnace was short cycling. I found your video, pulled out the flame rod and cleaned it gently with steel wool and it's working like a champ now. I will have it professionally cleaned later this week, but I won't have to pay emergency pricing. Again, thanks for the helpful video!

8 years of HVAC service. The best thing I used for cleaning flame sensors was a dollar bill.

Great video, thanks! My Goodman GPG13 GasPack decided to start short-cycling on me in the middle of a snow storm today. After watching your video, I cleaned my flame sensor and so far the unit is working fine. Total repair time from start to finish was about 10 minutes. You're awesome!

great vid! you are a good teacher. thank you

This video is a GEM. I spent several days troubleshooting my system, which was throwing a code for the pressure switch being stuck open. I replaced the pressure switch and the system worked for a day then the same problem recurred. The system board was telling me it was the pressure switch but it turned out to be nothing more than a dirty flame sensor rod. Steel wool, Done. Thanks for outstanding info.

I really like your videos..they are very informative! I have a 95% efficiency propane furnace. Recently it started short cycling on me. First thing I tried was cleaning the flame sensor. No Luck. I finally noticed through the window that only 3 of the 5 burners were lighting, causing the short cycle, not even making it to the flame rod. If I take the top cover of the furnace off before it shuts down, the last two burners fire. I ended up calling an HVAC tech who cleaned the burners and spreaders or wings. Still the same thing. It still short cycles. The intake and chimney are clear as well. Any ideas? I appreciate any input you can offer!

This was extremely useful. Furnace was short cycling in -15 F temps. House was freezing. This video saved us. THANK YOU!

One question I have my thermostat set to 72 degrees in winter. Every 5 minutes it turns on and off its that normal? I have a old digital Honeywell AM PM thermostat.

Had this exact problem for a few days. Watched the video,and went to work. It was the flame rod!!! Cleaned it up,and the unit is good as new. Thanks for posting your videos. In this time of money being short for me right now,this was cool to do it my self. Thanks again for what you did for my family. Last night it was 48 degrees where I'm at. We are warm now.... hugs to you sir

When I fixed my furnace ( I'm 15 btw) I figured that the problem had to do with the ignition controller. There was cracked solder on the coil probably from rapid hearing and cooling.

Gray, You rock! Like Javed below, you saved me a repair on my furnace. I had been through the level 1 diagnostics and was still having short cycling. My furnace would run, light and about the time the air handler turned on, the furnace flames would cut out, the air handler would run until the manifold cooled, and the ignition process would start again, that process would repeat... Your tip about the pressure switch and the vacuum lines keyed me in to look into that. I noticed a little moisture in that line, but when I pulled the larger, 1/2" diameter vacuum line that ran into the base cabinet, i found it to be wet and nearly plugged with fines rust sludge. I cleaned that out and the unit runs great. Thank YOU sir, I appreciate it. May your good deeds come back to your and your family many times!

Mine wont even get to a short cycle. It just whines up to start pre glow rod, then shuts right off in 1 second and just repeats that.... What could that be? Im not an HVAC guy, I am a carpenter.... but it sounds like the induce draft motor is starting up.... and then it just shuts down with nothing else coming on... Is this a pressure switch issue? It works spotty.... sometimes it works, sometimes I have to shut down the system for a few hours for it to work properly again.

Awesome ! My furnace kept short cycling and it is supposed to be 10 degrees this evening but Thanks to your video I cleaned the flame sensor and the furnace is running ! Thank You So Much you saved me at least $80 to $100 and helped me keep my family warm !

The first thing you should check is the thermostat, if you have a digital thermostat then change the batteries. If you have an old mechanical thermostat then get a new digital thermostat. If that doesn't fix the problem then call a professional, untrained persons should not mess with gas/propane furnaces.

Thank you so much! You gave me a new option to consider in stopping my short cycling furnace, and it saved me a ton of money! You have made a positive difference in this world sir!

Just wanted to say thanks! I was able to get my furnace working again and your video saved me both money, and time spent shivering in my freezing house!

Thanks. I watched this video because my furnace wasn't working on a cold Sunday morning. Saved me a lot of money, all I had to do was clean the flame rod like you suggested. I really appreciate the self-confidence boost this gave me as well.

Just what I needed! Sensed that the furnace wasn't heating the way it used to; and on a cold night, winter storm, wind howling outside and temp dropping.... Found this video, symptoms matched - a few minutes, cleaning the ignitor rod and putting it back in - Bingo! Thank You!!

HOLY SMOKES!! Great video. Fixed our on going problem that we have been suffering with for months! Finally, at the end of the winter, I decided to "Google" our issue. The furnace now works like a Champ!! Thank you very much for your video assistance.

I'm retired HVACR and it's nice to sit through one of your vids just to stay fresh on my skills.

Thank you so much for the video! My furnace began short cycling last night and it got down to 28 degrees here in Wichita (with a three month old I was very concered). After cleaning the flame rod our Goodman is working 100%

My old Sears Fifteen (maybe 50 years old) finally gave up the ghost. Short cycling and wish I knew this! I love older things that were built to last. It's true, they just don't make em like they used to. Thanks for the info!

You are helping people stay warm this season. Thank you.

You dear sir is a life saver , It is -40 with the wind chill in Waterloo Ontario . This morning I came home from work and inside of the house was freezing cold , There was ICE building up on the windows inside the house . I check the intake and exhaust for the furnace and clare it at the outside of the house . I flick the furnace switch on and off and the furnace came on , I set the thermostat as high as I can then went to bed,I wore two pears of sox,3 pairs of jogging pants,a toke , a pair of welders mitts and a sweeter with 4 long sleeve T shirts , Covered up with two comforter in bed. When I woke up at 3:30 pm to pick my wife up from work and the house was freezing cold , The hinges on the front door Ice was starting to buildup on them. Tomorrow is family day in Canada and that means all stores , Businesses and heating and plumbing are close . I decided to head to Walmart and buy 2 electric heaters , Since I have 3 little kids and I am taking care of my mother and mother in law , They are both seniors (70s ) . My wife reminded me that I will have to use the Visa . I then decided to type in the furnace symptoms on You Tube and I clicked on your Video. In your video I saw the same symptoms as mine and you pointed to the flame rod . I then went into the garage and grab my socket set which was frozen and began removing the covers, Drip plate and finally found the flame rod, I took it out clean it and once I re connect it and re install everything . I turn on the furnace and it stay on and start to warm the house, We thank you a million . Thanks,

This just saved me a lot of money. Everyone said I should replace the furnace bcs it was too old but apparently it was just the flame rod!! Thank you!!

Truly Love this Info, Thanks Very Very Much!!!!! It was my flame rod, Clean it and Every thing is working Fine. Thought I would need to call a repair man. Your Instruction save me money,. Again Thank You Very Very Much!!!!!!

I don't know how much money I saved with this video, but your advice is priceless. Thanks.

Thank you! My furnace was short cycling just like the video was when the the flame rod was disconnected. I took it out, wiped it clean with a paper towel and a little bit of cleaner, popped it back in and the furnace works like a charm! Saved me a few hundred bucks from calling in a pro!

Thank you sir for sharing your knowledge. I had a short cycle condition and watched your video. The flame rod was coated with a white chalky film. I cleaned the stainless steel flame rod and the short cycle problem was solved. The furnace is back up and working fine. The furnace is a GMPN060-3.

YOU THE MAN! My furnace fit your description to a tee. Used a little steel wool on the dirty rod and was back in business. Thank you.

Thank you so very much!!! My girlfriend and I had our furnace doing this exact thing and we cleaned the heat rod and thermocouple and it works like a gem!!! You are awesome!!!! God bless you!

You are DA MAN -- just saved me a call out for a simple fix - tried the flame sensor rod and made no difference so on to step two and the pressure sensor tube was full of water .. drained that and heat again :):) Around here it takes a couple of days to get someone to do a house call so would have been cold for a few days as well as the cost. BIG THANK YOU !!!!!

The fact this video was made over 4 years ago and you're still in here helping people all the time is incredible. You also solved my issue so thanks for that! Do you have some sort of donation page?

I remembered watching this video awhile back and low and behold my furnace started short cycling today! Took a little sand paper the flame rod and Hey ---It works!! Thanks You!!

SWEEEEEEET SHIT!!!!!!!!!!! woke to a freezing cold house this morning and a furnace not running. changed air filter and then watched your video.Cleaned the fire censor and it's been working sence. thank you for saving me $100.00 on getting a repairman out here to do 10 minutes of work I just did.

Just want to say I really appreciate you posting this video. I was noticing the same 4-8 second cycle with the burners lighting and then shutting off. The system cycled just like you described. I pulled out the flame detection rod and it was indeed scored up-and-down. After cleaning it with light sandpaper and replacing it my furnace is now on with the burners lit and running for longer than it has in a while. Thank you!

Thanks so much for taking the time to post this. It took less than five minutes, was an easy fix and took care of a problem I'd been having intermittently for a while now. Thanks again.

So that's why my furnace was doing that. Thank you very much! 125 thumbs down? Some unhappy repair people missing out on an easy boat payment?

thank you so much! If it wasn't for you taking the time to put this video up, my family would have been in the cold. We greatly appreciate you.

Thank you! This is what mine is doing. I'll pull it out, clean than check it for continuity.

You're great !!! My furnace was doing exactly what you demonstrated. I pulled the flame sensor, polished it off with Scotch Brite, reinstalled it, and, BINGO, working just fine !!! Thanks a lot, you just saved me a $159.95 service call, and who knows what they may have tried to sell me. !!! I appreciate it very much, again, thanks a lot.

Thanks for taking the time to share your experience with furnace problems, very helpful

Thanks for posting this video, it was extremely helpful! It is currently -3 here in Erie, PA and our furnace wouldn't work. Through your video I was able to figure out the trap below the condenser was plugged and not draining. We'll be warm tonight thanks for your video! Thanks again!

I know very little about furnaces and this video worked like a charm. Thank you

Excellent video, very informative and easy to follow. Thank you for a great overview, I'm gonna start with the rod as you suggested and see if she stops short cycling. Thank you!

Best video I have seen on this problem. Thanks very much for the help.

Thanks, my furnace is cycling but working & here in St. Louis, MO we getting the coldest winter since 2014. So I'm not going to touch since it's working but after Thursday we will be above 45 degrees. I will clean that flame rod. I cleaned the flame sensor Jan 3, my HVAC son changed the igniter & it was fine until a few days ago

Thank you so much for this video. Sandpaper to the flame rod worked for me. My warm little kids appreciate your advice. you saved me a pile of money. subscribed!

Thanks for the info. Furnace is running normal again. Glad mine didn't happen durring the heart of our Minnesota winter.

Fixed my problem, Dirty flame sensor. Thank you so much!!!!! Saved my hundreds on a repair man

thank you so much my husband is always on the road so im left to handle these issues which when having little kids you cant go without heat in the onset of cold weather it seems to be the starter im always so scared that im going to break things and make them worse then they are and as you know furnaces arent cheap to have fixed so i always research before going at the issue blind with no knowlegde so thank you again for this its helped

this video just saved me some $$$ and very cold days here in the northeast/Adirondack Mountains..i spent 2 days checking connections/cleaning intake vents/filter/changed pressure switch for my furnace that was doing this short cycle..the error code told me it was pressure switch but, i did what one of videos said not to do-(swap out pressure switch at the beginning of trouble shooting)..I DID NOT WATCH YOUR VIDEO ON SHORT CYCLING FURNACE 2 DAYS AGO WHEN PROBLEM STARTED..it was a dirty/corroded flame sensor that was the culprit, cleaned it with emory cloth and reinstalled the flame sensor and also reinstalled the original pressure switch and the furnace stopped short cycling and works fine now..i was heating with 2 propane mr heaters & fans for 2 days with 18*f temperatures outside, it was very brisk in here..i called a tech to come and because of the season here the tech was 5 days back logged and scheduled me for tuesday, today is saturday and life is better when i am not in my living room watching the game with winter coats/gloves and hats/scarfs on lol...thank you very much from the Adirondack Mountains..

It could be the inducer fan that's running. If it does not see the proper pressure in a fixed time period, it shuts down. Any possible snow or ice on the vent? GFM

Thank you. I did some looking and I figured it out. And my furnace fired right up the first time! Been working all day. I appreciate your video!

You are truly a life saver. My furnace kept short cycling on me. After your vid and a quick clean of my flame sensor rod all was well.

Thank you for this video, this video was helpful in my husband and I getting our furnace to work after we cleaned the flame censor. Needless to say this saved us time, money and a cold night in our home since the furnace stopped so late at night.

Excellent!! Cleaned the ignitor and works like a charm. Thank you Gray!!

Thank you your video. I cleaned the sensor and 15 minutes later I have heat again. Very much appreciated

Thank you! my house is warming up, gotta stay warm in Cleveland's spring snow storm!

I thank God for you and this video you really got me out of a tough Jam I was frustrated until I ran across your video thanks a million may God 🙏bless 🙏 you and your family 👍

Great video! Turns out it was the anticipator on my Carrier thermostat.I set the pointer to match the amperage on the new gas valve I installed. Furnace now functions great.

Thank you for the video. When I went to remove my flame sensor to clean it (it wasn't very dirty) I discovered the retaining screw had come loose and it wasn't all the way up into the flame. I cleaned it anyway and secured it tightly and the problem was solved.

I'm not in the trade, but I do industrial automation, so modern furnaces are easily understood. It's a good thing you are doing because there are sharks in the water who would happily sell you a furnace rather than fix the smallest problem. Even if the home owner doesn't want to go outside their expertise, having an idea what's wrong could save them big bucks.

Spot on , ONCE AGAIN!!! KEEP UP THE AWESOME VIDEOS. THEY ARE MUCH APPRECIATED BY ALL!

Thank you so much for your post. You was very clear and thoroughly explained the exact problem that we had and I can tell that you are a true expert in this . Now we have an ideal what is wrong.

Great Video! Diagnosed the issue and the fix saved me a service call. I have heat in the house again!

Thank you for the video. Your explanation and visual demonstration was very helpful. I cleaned my flame sensor and it solved the issue.

As a rule, the furnace should run about 5 to 7 minutes. This obviously depends on outside temp, furnace size, insulation amounts, etc. Hope this helps. GFM

I have a green scrubber pad, the type safe for non stick cookware. Been using it for years and my furnace never gives me any trouble. Forgot to do it this year, and sure enough it short cycled. Cleaned the flame rod and it's working perfectly again. If it's safe for nonstick pans, it should be ok on the rod.

Cleaning the flame rod totally worked! Thanks!!!

Thanks for the great tip about the flame sensor rod. This was the problem in my case, and it is now solved!

We need these kind of valuable education. Thanks for the nice post

Thank you....this is just what I needed to fine. Very clear instructions. I sanded the flame rod and now my furnace is heating my house up again!!

Thanks for the info. while checking my system, I found an insulation panel had fallen on top of the fan. That was causing the problem and I had very low air flow, so definitely check physically before paying someone to look!

Thank you! A little compressed air and passes with a little sand paper, back to working for the moment!

i cleaned the sensor with sanding paper , so far so good , thanks for help , u did a great job , posted video on RU-vid u got blessing because my furnace got this problem at night and we got season snow at the moment and i was thinking if this not get fixed we will be in trouble , once again thanks for sharing

Thank you sir. Thank you thank you thank. Because of your video, my furnace is now working.

Many thanks, I just cleaned our rod in 5 minutes and the furnace works again!

This solved my problem! I just saved about 100-300$ thank you!! Amana 80 SSE was the make/model. Thanks dude