Question about Heating & Cooling

2 Answers

Lennox Gas Furnace that turns on and shuts off in minutes

The unit will turn on and run fine for a few minutes then shut off. It won't immediately turn back on, almost as if it has to cool back down first. Any ideas?

Posted by on

  • 5 more comments 
  • jros5 Nov 19, 2008

    I have the very same issue and I'm troubleshooting it now. What's interesting is that it'll sometimes fire and stay on for a long time. I replaced the thermostat upstairs on the wall and it seemed to work overnight but in the morning, same problem. I could get it to kick on with the thermostat, but it would only fire for about 2 seconds and stop. It would cycle again and fire after 7 seconds, failing again after 2 seconds (it would repeat this until I killed power to the furnace completely).



    The unit has been operating normally now for about an hour, so the house is warming up. When it's warm enough to give me time to mess with it, I plan on trying to eliminate a short in the wiring from thermostat to the furnace control board. I will do this by jumping a wire on the control board between the red and white wires to complete the circuit, as the thermostat would. If it operates flawlessly and stays fired when hot or when cold, then it's either a short in the wiring or something with the thermostat (doubtful as I replaced that already...*however* the first replacement was broken out of the box--I had to return it for another).



    I'll update with my progress...

  • richardsdm Feb 02, 2009

    Have a Lennex/Armstrong gas furnace. Approx. once a week furnace will try to cut in and then quit after a few seconds. Get a flash fault code of 3 - Pressure switch open with inducer on. What does this mean, what is the likely cause. Furnace is only 3 years old. I can turn off power to furnace and turn back on and it is ok for a few more days. Solutuions???

  • aocomp
    aocomp Dec 02, 2013

    there are two gas circuits, pilot and main.

  • Dan Fidoe
    Dan Fidoe Mar 05, 2014

    Drain line. Mine was clogged. Fixed the issue.

  • Dan Fidoe
    Dan Fidoe Mar 05, 2014

    Clogged Drain Line. Fixed my issues.

  • Dan Fidoe
    Dan Fidoe Mar 05, 2014

    http://www.youtube.com/watch?v=maZ4JskGj...

  • BAJ1 Mar 11, 2017

    I had to do this when mine was about 20 years old, could not believe the crud in there. I could actually hear the condensated water gurgling in the pipe while it ran. Not exactly routine maintenance, but something you will most-likely have to do eventually if you keep running these units long enough.

×

2 Answers

  • Level 1:

    An expert who has achieved level 1.

    Governor:

    An expert whose answer got voted for 20 times.

    Corporal:

    An expert that has over 10 points.

    Mayor:

    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer

After troubleshooting like mad, I found that the flame sensor (rod that sits within the flame) was fouled with carbon on the surface. I believe this shields the rod from proper heat detection and the sensor reports that there is no flame and to shut off the gas valve to avoid explosion. Once I pulled out the rod and cleaned it with a wire brush, I have no problem whatsoever--fixed.

Posted on Nov 20, 2008

  • 1 more comment 
  • lander guy Nov 11, 2010

    If you don't have a wire brush, try sandpaper. IT worked for me. I have nothing but warm thoughts of you. lol Thanks.

  • godiva1004 Dec 17, 2010

    I have a "lovely" Lennox furnace that does the same exact thing and after calling out a repair person and standing next to him to watch what he did, he used sandpaper to scrub the carbon off the flame sensor rod and put it back in place. He told me some repair places will tell you you need to buy a new one (which is expensive) but they are notorious for doing this every couple of years so just clean it yourself until you absolutely need a new one. It seems nothing is built like it used to be. :(

  • BAJ1 Mar 11, 2017

    This isn't a product quality issue, it's routine maintenance. The igniter (spark plug) will wear out too, just like the ones in your car. Also make sure the connections are tight. I tested mine with an Amp meter and was getting 0uA (microamps). I went to pull the sensor and found that the threaded coupler on the end of the sensor was loose. I put a wrench on that (just got it tight, didn't torque it) and was then getting about 2uA from the sensor after the burner lit-off. I don't know how much current it is suppose to create, but 2uA was enough to keep mine running.

×

  • Level 1:

    An expert who has achieved level 1.

    Mayor:

    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer

I have a Lennex Gas Furnace, It turn on and stay on for about 20 mins then turns off. You can hear the electronic ignition trying to stay the furnace but nothing sometimes after four or five tries it will come back on, but it never warms my house to the temp. set.

Posted on Jan 07, 2011

2 Suggested Answers

  • 215 Answers

SOURCE: The unit will turn on and run fine for a few

The ignitor will light, the blower will start up and run for a few minutes and then the system will shut down, and the blower will continue to run and cool down. The ignitor is not working properly, the ignitor has carbon build-up and need to be removed, cleaned all the black carbon from the ignitor with a little piece of sand paper and replaced, turn the heat back on and this should correct the problem.

Posted on Dec 14, 2009

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

2 Answers

The heater runs for a few minutes and then it turns itself off it's on stable ground and everything


My furnace keeps shutting off, only runs for about 5-10 mins ...

? 5:19
https://www.youtube.com/watch?v=pEng9mtBtKk
Dec 15, 2013 - Uploaded by shannon122005
My furnace shuts off before reaching the set temperature on the... and then i turn switch back on , the furnace running about 4-5 hours and then ...

Furnace starts, then shuts off. - Home Improvement ' DSLReports Forums

www.dslreports.com > ... > Home Improvement

DSLReports
Dec 1, 2009 - 30 posts - ‎18 authors
[HVAC] My gas furnace cycles off every 6 minutes. ... This cycle will repeat a fewtimes, then usually after the second or third time everything ... How long is it after the big blower cuts on that the gas shuts off? ... Turn the furnace on, once the inducer blower is running you should read 0 volts (switch is closed).

Jan 03, 2016 | Heating & Cooling

1 Answer

Furnace starts and ignites and fan comes on but when thermostat is turned off the gas shuts off and flame off but furnace continues to run. whu?? any suggestions?


The fan normally runs for a few minutes or so after the gas shuts off.

This removes the heat from the furnace and transfers it into the living space instead of just letting it possibly cause overheating of the furnace until it dissipates. If it is a fan that blows outside, that fan also needs to run for a few minutes to clear exhaust gasses from the furnace - to keep them from dissipating into your home.

Sep 28, 2015 | Heating & Cooling

1 Answer

I have a Ducane MPGA100B4B gas furnace. The furnace only runs for about a minute then shut off. It does this far too frequent.\r\n First the induce draft blower turned on for a few seconds to check for...


Hello, sounds like the limit switch is opening on the furnace.Usually when a furnace goes off on its high limit is becuase the airflow is being restricted making the furnace overheat. a limit switch is there to protect the furnaace from overheating, most cuases are either dirt or the blower motor not running up to speed, anything that cuts down on the airflow will cause the high limt switch to open.

Feb 24, 2011 | Heating & Cooling

1 Answer

Garage furnace (standing Pilot) pilot stops after 30 mins.


it sounds like the afc the fan control not working could be dust on the afc

Jan 10, 2010 | Dayton Gas Furnace Heater

1 Answer

The unit will turn on and run fine for a few minutes then shut off. It won't immediately turn back on, almost as if it hans to cool back down first. Any ideas i have a lennox furnace


The ignitor will light, the blower will start up and run for a few minutes and then the system will shut down, and the blower will continue to run and cool down. The ignitor is not working properly, the ignitor has carbon build-up and need to be removed, cleaned all the black carbon from the ignitor with a little piece of sand paper and replaced, turn the heat back on and this should correct the problem.

Dec 12, 2009 | Heating & Cooling

2 Answers

Lennox furnace 17 yeanrs old. flame comes on and the shuts down sometimes right away some times in a few minutes. We have the furnace go down to 58 at night. It takes all day to get back to 67.


Sounds like a dirty flame sensor.
Also 9 degrees is a large swing to recover. Most specialist will advise no more than a 5 degree set back, otherwise recovery time eliminates any savings you may achieve.

Dec 05, 2009 | Dayton (3E407) Heater

1 Answer

My Lennox gas furnace runs for approximately two minutes and shuts off. Normally the blower runs for a few minutes but no longer is this the case. My furnace repair man cleaned the flame sensor and it...


if the unit has a flame (gas valve opening)the problem may be the fan going bad or fan relay -- sounds like unit going off on high limit control

Nov 01, 2009 | Heating & Cooling

2 Answers

Lennox G40UH(x) series - Air not coming on


electrical connections @ the furnace may the thermostat .Tom

Jun 18, 2009 | Heating & Cooling

1 Answer

My blower motor will not stop running,and my ignitor doesn't light.


I am assuming you are talking about a Natural Gas or LP furnace. The blower motor is powered by a separate 120 volt circuit, so flipping the 240 volt breaker for the furnace will not shut it off. There should be a regular light switch at the furnace that will turn off the blower for servicing the unit. When you take the cover off the unit, there should be instructions on how to re-set the igniter. If it won't re-set, try shutting off the gas for a few minutes, then turn it back on and then reset. If none of this works, and you can't find the owners manual, call a service technician.

Feb 22, 2009 | Electric Circuit Breaker Kit for Furnace

Not finding what you are looking for?
Heating & Cooling Logo

Related Topics:

14,255 people viewed this question

Ask a Question

Usually answered in minutes!

Top Heating & Cooling Experts

paulcarew

Level 3 Expert

2364 Answers

Dan Webster
Dan Webster

Level 3 Expert

8205 Answers

Donni Steen

Level 3 Expert

659 Answers

Are you a Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...