How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Edward Your Own Question

Edward, Handyman
Category: Home Improvement
Satisfied Customers: 7966
Experience:  Handyman, Master Gardener
Type Your Home Improvement Question Here...
Edward is online now
A new question is answered every 9 seconds

My furnace will start to run then shut off

Customer Question

When I flip the switch on my Colman Evcon unit, sometime it will come on and heat for 2 to 5 minutes and then shut off. Other times the unit will act as if it’s trying to turn on and then shut right off.   This can go on two or three time in a row. Then it will sit quite for 30 minutes to an hour. Then try to kick back on. I have watched the idiot light on the unit and it blinks at a steady bright/dim indicating all is normal. I have tried replacing the thermostat and that did nothing. I have also jumped the red and white wires together to see if it will run continuously and it does not.   I had what I believe is called the vacuum switch or valve? I am stumped to what the problem might be?
Submitted: 8 years ago.
Category: Home Improvement
Expert:  Edward replied 8 years ago.

Hello Customer,

Thank you for asking your question on Just Answer.

Could you explain your situation a little more?

What is the make and model number of the furnace?

When was the last time the furnace was professionally serviced?

What is the age of the furnace?

What fuel does the furnace use?

What have you tried to correct the problem?

Do you have a digital camera that you could use to send pictures of the furnace if needed?

Thank you again for trusting us with your problem.

Please reply as soon as possible so that we can finish answering your question.

Customer: replied 8 years ago.
Reply to Edward's Post: The unit is a Colman Evcon, Model BGM08012CX, SNNNN-NN-NNNN the age is 14 years old, it runs on natural gas. The unit was last serviced about 5 years ago.

In my original e-mail I mentioned what I have done to correct the problem.

I do have a camera and I can take a photo of the area you would like to have the photo taken.
Thanks, Floyd
Expert:  Edward replied 8 years ago.

The first thing I would suggest checking is the flame sensor. It will cause the problems you have describes. The flame sensor can be cleaned with a wire brush or sandpaper. The flame sensor very seldom become defective, unless their ceramic base cracks. Check the base for cracks while cleaning the flame sensor and replace the sensor if the base is cracked. This problem can also be caused by lack of cleaning the furnace and having the burners cleaned.

Many homeowners do not realize, the complications of not having a professional inspect the heating system yearly, can cause. If a fire, or worse, is caused by the furnace and there are no records of the furnace being maintained, the insurance company can and will deny the claim for damages. I have worked on systems after they have caught fire and the homeowners got no help from their homeowners insurance for the damage. I have installed furnaces in new homes that the owners were building to replace a home that was destroyed by fire from not having the furnace serviced. I like every customer to have this information to consider before repairing the furnace themselves.

Customer: replied 8 years ago.
Reply to Edward's Post: When I had the heating guy out to check the furnace, he said the unit looked really good and he cleaned out any build up he could find.

He first said it might be the sensor panel??? He said an easier replacement and cheaper item that also could cause the problem is vacuum valve, he was able to run the burners at full blast and they ran until he shut them off. This had something to do with a connection he made inside the furnace box.

So I question the flame sensor. Is this normal on a Colman and have you worked specifically with these units?

Thanks for your feedback. Floyd
Expert:  Edward replied 8 years ago.


Yes the flame sensor is a common part and all gas furnaces unless they are a very old model. Yes, I have worked on Many Coleman Furnaces and assisted several customers with repairing their units. Click here for information about the flame sensor.

Should you require further clarification, never hesitate to ask. It would be my pleasure to clarify my answer to your question. If after reviewing the above information, you have additional questions, I will be glad to answer them. My goal is your 100% satisfaction with all questions I answer.

Please click the green ACCEPT icon if you feel I have given a complete answer, and you are satisfied with my answer. Positive feedback and bonuses are always greatly appreciated!



As always when using Just Answer your accept is required for me to be paid. Please do not accept unless you are 100% satisfied with the answer.

Please do not accept my answer if you do not feel comfortable with my qualifications or the information I provide. If you accept my answer please leave feedback.

Expert:  Edward replied 8 years ago.
I saw you have viewed my answer but have yet to accept any of my answers. Do you have additional questions?
Customer: replied 8 years ago.
Sorry for the delay. I just got off the phone with the Heating guy who has been working to fix my furnace. I wanted to find out first if he had checked the flame sensor. He said it was the first thing he checked, he pulled it out, cleaned it off and there were no cracks.

The way the furnace acts, is when you turn on the furnace from the thermostat, you hear the electronic inducer engages and then it shuts off before the flame sensor picks up. This can happen 2 or 4 times before the system fires and you hear the burners running at full force. However that becomes short lived. It may run for 2, 3 maybe even 5 minutes and then shuts off. If you turn the thermostat off and back on, it's as if it resets the system and the process starts over.

Any thoughts? Thanks, Floyd
Expert:  Edward replied 8 years ago.
Thanks for the reply and the additional information. The draft inducer (electronic inducer) has a tube connected to it that goes to the pressure switch. The pressure switch checks for the correct air flow in the duct. After the pressure switch stops the furnace from operating 3 times it will cause the lights to flash and the furnace will have to reset to try again.

The tube that connects the draft inducer to the pressure switch can get dirt in it. This will cause the pressure switch to shut the furnace down. The ports that the hose connects to can get stuff in them also. This can be cleaned out using a small wire. Do not blow into the pressure switch or it will be damaged and will need to be replaced.

Other things that can cause a problem with the pressure switch shutting down are dirty filters, an A coil that needs to be cleaned, any blocked return air vents, dirt on the draft inducer blower blade, dirt on the furnace blower blade and a obstruction in the chimney that would keep the chimney from getting a good draft.

I believe one of these are causing the problems you are having.

Please do not accept unless you are positive you are 100% satisfied with the information provided. Let me know if you would like me to opt out and have another expert assist you.

Customer: replied 8 years ago.
Reply to Edward's Post: We have replaced the pressure switch already, so I know we are good there.   This was the least expensive item to replace so we tried it first. What about the master switch board (not sure what it is actually called) the box on the unit that has the idiot light on it that blinks to tell you how the system is working? This was also suggested as an item they might be causing the problem. As I mentioned in one of my earlier responses, this light never changes from a normal bright/dim blink.

Thanks, Floyd
Expert:  Edward replied 8 years ago.


You have done a very good job at providing the information and trying to correct the problem. The main board of the furnace is expensive and to continue to replace the parts that are not known to be the problem will get very expensive fast. I am going to opt out of answering this questions since the only suggestion I have left is to have a professional that can be there to diagnose the problem, diagnose and repair the furnace.




Customer: replied 8 years ago.
Reply to Edward's Post: I will await your colleague’s thoughts. I am thinking we need to replace the main board, and I realize the cost is much more then the items we have tried so far. It would be great if there is a solution cheaper that what has been tried, but I am not feeling that is the case.

Thank you for your time… Do I accept your request before we move on (opt out)?

Thank you, Floyd
Expert:  Edward replied 8 years ago.


Please do not hit the accept icon until you have the needed answer. It was a pleasure to try and provide you the answer you needed to repair your furnace, but to continue could cost you to spend money that may not be necessary. My goal is 100% customer satisfaction with all customers who accept my answers. Since I have not provided you the information needed to repair your furnace do not accept until you have the needed information.



If another expert has the answer, hopefully they will respond soon.

Customer: replied 8 years ago.
Thank you for your time. Happy New Years, Cheers, Floyd
Expert:  Edward replied 8 years ago.


You are welcome. Hopefully you will get a response soon.

There is no need to reply to this post unless you have additional questions. It will only generate a request for me to reply to your post.



JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
< Previous | Next >
  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
  • Thank you for the expeditious answer. It's good to know you're out there and awake in the wee hours when I finally have time to ask questions about my Jenn Air. Jean Riverhead, NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY

Meet The Experts:

  • Brian



    Satisfied Customers:

    Licensed Architect- 17 years, L.E.E.D. AP
< Last | Next >
  • Brian's Avatar



    Satisfied Customers:

    Licensed Architect- 17 years, L.E.E.D. AP
  • The Home Smithy's Avatar

    The Home Smithy

    Home Builder

    Satisfied Customers:

    #1 Home Improvement Expert 30+ years experience
  • Steve G.'s Avatar

    Steve G.


    Satisfied Customers:

    VP of electronic repair company and home theater advisor.
  • StructuralEng's Avatar


    Civil Engineer

    Satisfied Customers:

    Licensed Structural Engineer
  • Eric M. Bright's Avatar

    Eric M. Bright

    We Don't Comprehend the Word Can't!

    Satisfied Customers:

    I've been been doing things for my clients that others have said cant be done for over a 1/4 Century
  • Rich's Avatar


    Home Improvement Enthusiast

    Satisfied Customers:

    Over 35 years construction and home maintenance experience
  • Phil's Avatar


    Mechanical Engineer

    Satisfied Customers:

    Retired contractor, 51 years experience