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 Matthew Your Own Question

Matthew
Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 1994
Experience:  14 years experience in the HVAC field of service, installation, Manual J & D calculations
6927568
Type Your HVAC Question Here...
Matthew is online now
A new question is answered every 9 seconds

Bryant gas furnace will not light, I smell no gas and there

Customer Question

Bryant gas furnace (Model #310AAV066110AAJA) will not light and heat. I smell no gas and there is no sound or sign of igniter activity as would normally happen when it sparks and lights gas. Fan can run if we set our thermostat to Fan "ON" mode rather than "Auto." If I turn the thermostat "Off" and back on to heat it will start up for a moment but never produce heat and just stop. Restarting the unit over and over will not get it to light up and heat. We already had to replace the igniter with a new one two years ago, but it still looks fine. The furnace is a whopping 5 years old maybe.

In the lens inside the front cover the red LED/indicator blinks slowly a few times and stops, then stays on a while, and repeats the same.
Submitted: 4 years ago.
Category: HVAC
Expert:  Matthew replied 4 years ago.
Is the inducer draft motor running?
Customer: replied 4 years ago.
Not sure, I do hear a motor sound other than the main fain as the unit attempts to start up, but how do I check it, can I do this with the main front cover off?
Expert:  Matthew replied 4 years ago.

The inducer motor is the small motor hooked to the vent pipe going out of the house. This is the very first thing that comes on during a heat call. This has to be running in order for the pressure switch to prove and allow the igniter to light.

 

Find the pressure switch it will look like this.

 

 

There will be a rubber hose that attaches this pressure switch to the inducer draft motor housing. Take this rubber hose off and blow through both ends. Then take a paper clip and clean out the tiny port on the inducer housing where this hose slides on.

 

Put it all back together and try the furnace again. Let me know what happens.

Customer: replied 4 years ago.
Ok that device and hose was found, tube was fine and is clean inside, air goes through AOK. furnace does buzz a while when on.
Expert:  Matthew replied 4 years ago.
This blink code you are seeing will give us an idea of what is failing. The code is a two digit number the first digit is the number of short blinks the second digit is the number of long blinks then it will repeat. So find out what this code is for me please sir.
Customer: replied 4 years ago.
I can, tried before but seems confusing.

On a sidenote: There was a bit of a hot smell at least once I noticed that in the world of electronics would tell me I need to find a bad electrical part.

Also on the top of the gas pipe I noticed some shredded material like a little bit of leftover wood carvings...odd. Did that come down from something above it in there? Outside of furnace covering is clean.
Customer: replied 4 years ago.
Ok I watched that LED several times through its cycle. I believe what I am seeing is one very short and two long. 1 Short, 2 long, and then it repeats
Expert:  Matthew replied 4 years ago.

not sure what the wood is may be they drilled a hole in a board or something above the furnace and these shavings dropped down on it.

 

From you describing a burning type electric smell and the humming noise you referred to earlier I think your inducer motor may be bound up and not turning. This would cause the furnace to not ignite.

 

Let's do this.

 

 

Take the two wires coming off of the pressure switch you found earlier I believe they are an orange and a yellow wire. Turn the power to the furnace off and unplug these two wires.

 

Now with the wires hanging unhooked turn the furnace on. Once power is restored to the furnace connect these two wires together with a piece of metal of some sort. No worries this is just the common side of a 24v circuit it will do you no harm. At the very most it will give you a tickle if you happen to touch he actual metal on the plugs it will feel like a 9v battery when you stick your tung on the end, but just handle the plastic sheath on the wire only and you will be fine.

 

With these wires hooked together see if the igniter glows. Let me know.

Expert:  Matthew replied 4 years ago.
that is code 12. code 12 is displayed any time you cut power to the furnace off and back on. it will flash this for 90 seconds with the main blower running and then it will either go into ignition sequence or it will become a different blink code telling you what the actual fault was.
Customer: replied 4 years ago.
I think I agree that induce motor is suspect as we have heard some odd noises from the furnace recently when it ran, was not main fan doing that.

OK I tried removing and shorting those two connectors together, no joy.

Does it take an HVAC person that can work with Gas to replace that?
Customer: replied 4 years ago.
FYI - I have multimeters and am a long time pro at electronics so I am fine with testing things, low voltage especially
Expert:  Matthew replied 4 years ago.

bypassing the pressure switch like this should make the igniter come on. When you say you shorted the two connectors together you mean you connected the two loose wires correct?

 

This should make the igniter glow unless the igniter is bad. By connecting these wires together we have eliminated the venting system from the equation.

 

The only thing is that you must allow the furnace to send the signal to the inducer motor to start up before you can short out the two wires. So it is essential that you start the furnace up with the two wires unhooked then after about 10 secs once the furnace power is restored you hook them together or the bypassing will not work.

Expert:  Matthew replied 4 years ago.

Awesome!

 

Ok lets test the igniter then.

carrier-furnace-igniter-doesnt-glow-ignitor_hot_surface_bryant_lh33zs004.jpg" alt="" width="77" height="116"/>

unplug the igniter at it's little white male female plug connector.

hook the pressure switch back up the way it should be.

Now let the furnace start up and see if you are getting 120v to that plug going to the igniter. with one lead on each prong of the plug it should show 120v.

Take in mind it takes a good 90 seconds for this signal to be sent to the igniter once power is restored to the furnace and the inducer motor comes on.



Edited by Matthew on 3/2/2010 at 4:27 PM EST
Customer: replied 4 years ago.
I connected the two together hard as instructed, after disconnecting. Maybe not a full 10 seconds. I can try again. Also do I have to shut the breaker off to the furnace or is the wall switch by the furnace that turns it off (or A/C) enough? At no time did that inducer spin. I did not notice a glow on igniter but can try again. THere was no popping or sparking sound

Were those codes no help?
Expert:  Matthew replied 4 years ago.

the switch on the wall is fine.

 

 

I posted earlier about the codes I will cut and paste what I said here again.

 

that is code 12. code 12 is displayed any time you cut power to the furnace off and back on. it will flash this for 90 seconds with the main blower running and then it will either go into ignition sequence or it will become a different blink code telling you what the actual fault was.

 

Now when you cut power off then back on you have to let the furnace go thought this 90 second purge while it blinks this code 12. After this 90 seconds then you can go into bypassing the venting system like we talked about earlier.

Customer: replied 4 years ago.
OK, the LED goes solid on after the 90 seconds, so no error code then.

I saw the inducer motor outer spinner/fan gizmo try to move and I helped it a little. Sure enough it tries to turn more and more, but is making noise and cannot really spin up. At that moment though the signals / power was obviously there to make it run.
Expert:  Matthew replied 4 years ago.

If the motor is getting the 120v but doesn't spin then that has to be the problem. You should be able to jump the pressure switch out like I told you earlier once the inducer gets this voltage and it should light the igniter and start the furnace, but if you can visibly see the inducer trying to spin and not spin then that is your problem.

 

http://americanhvacparts.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MOT21ZE123&Category_Code=m-im

 

that is the replacement motor for your furnace it is up to you if you want to try and do it yourself or if you want to get someone out there to do it. Just know that if you purchase parts on line and they are not installed by a licensed professional the manufacture has the right to void the warranty on your furnace.

Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 1994
Experience: 14 years experience in the HVAC field of service, installation, Manual J & D calculations
Matthew and 5 other HVAC Specialists are ready to help you
Expert:  Matthew replied 4 years ago.
You stated in your very first post that this furnace was only 5 years old so I would think this part is still under warranty.
Customer: replied 4 years ago.
Do we need the draft-inducer motor for the unit to run safely, so if we bypass to see if the furnace runs otherwise? I plan on getting the part asap if I cannot clean it up and make it work smoothly again.
Expert:  Matthew replied 4 years ago.
the bypassing of the inducer system is only for testing correct. You can not run the furnace without an exhaust system working properly. This would be very unsafe.
Customer: replied 4 years ago.
What I thought, thanks Matthew. Here is what we did though, removed the part, dusted her off and shot lots of spray lube into the bearings only, cleaned up any excess lube and reinstalled. Furnace now working fine!
Expert:  Matthew replied 4 years ago.
Good deal. It could have just been catching on something causing it to stop and start. hopefully you will get some life out of her, but this could not have been good on the internal windings so you may just want to look into seeing if you can get it swapped under warranty. A furnace this old should not have these types of issues.

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... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...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
< Last | 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
  • 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
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • gotoman for ac

    HVAC Technician

    Satisfied Customers:

    4657
    51 years of experience install design and repair of all makes and models of AC
< Last | Next >
  • http://ww2.justanswer.com/uploads/SE/ServiceTechRus/2012-6-7_2119_056.64x64.JPG gotoman for ac's Avatar

    gotoman for ac

    HVAC Technician

    Satisfied Customers:

    4657
    51 years of experience install design and repair of all makes and models of AC
  • http://ww2.justanswer.com/uploads/AL/alumalite/2012-5-10_234018_shutterstock506249951forJA500.64x64.jpg Phil's Avatar

    Phil

    Mechanical Engineer

    Satisfied Customers:

    3888
    Retired HVAC/ Electrical & Boiler contractor. Industrial
  • http://ww2.justanswer.com/uploads/skibum0101/2008-12-16_015819_just_answer.jpg Rick Mather's Avatar

    Rick Mather

    HVAC Technician

    Satisfied Customers:

    3132
    35 years experience, HVAC
  • http://ww2.justanswer.com/uploads/RY/Rygis20/2011-5-7_3143_DSC5324.64x64.JPG Matthew's Avatar

    Matthew

    HVAC Technician

    Satisfied Customers:

    1994
    14 years experience in the HVAC field of service, installation, Manual J & D calculations
  • http://ww2.justanswer.com/uploads/KE/kentguidry/2011-9-26_214316_0059.64x64.jpg Kenton Guidry's Avatar

    Kenton Guidry

    HVAC Technician

    Satisfied Customers:

    962
    12 years install/service experience.
  • http://ww2.justanswer.com/uploads/solarman1947/2009-12-13_223915_phpkKBcXq_c2PM.jpg Rick Ridley's Avatar

    Rick Ridley

    UK Heating Engineer

    Satisfied Customers:

    871
    Retired But have had 30 years on the tools, Ex CORGI
  • http://ww2.justanswer.com/uploads/Ironheadfan/2009-12-18_222416_pump_005.jpg Tom's Avatar

    Tom

    HVAC Technician

    Satisfied Customers:

    770
    16+yrs HVAC/R service. Residential Commerical Industrial