# Bryant plus 90 furnace won't ignite-code 31.



## nina01 (Mar 25, 2009)

Please help. My Bryant plus 90 furnace (model 350 MAV) goes through the ignition cycle, but does not light. It provides a fault 31 code. I have verified operation of pressure switch based on directions in my owners manual. I hace cleaned the ignitor rod, vacuumed the burner ports, and cleared all obstructions and vent restrictions. The inducer motor works. Does anyone have any ideas? Thanks.


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## kenmac (Feb 26, 2009)

On the blower door it should tell you what that code is,,,,Pressure/vaccun switch, ignitor.. When it goes through it's operation do you hear a click at the g.v. & smell any gas ?


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## nina01 (Mar 25, 2009)

The code is 31. The manual states that this is the pressure switch. There is no smell of gas. The gas valve does not open--it doesn't get to this point in the cycle. The start cycle initiates, but the ignitor fails to glow. The gas valve will not come on.


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## qbert (Mar 23, 2009)

I would check and clear condensate drains, and look for intake/exhaust obstruction


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## kenmac (Feb 26, 2009)

check the vent for obstruction.... check that the vaccun line is clear.check that the vent motor is pulling vaccum... You can jump vaccum switch at the 2 wires & see if it comes on . If it's bad...vaccum switches don't cost much


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## Plumber101 (Feb 25, 2009)

Have seen build up in the port where the hose off the pressure switch connects at the inducer or collector.


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## Plumber101 (Feb 25, 2009)

First I would like to thank you for not keeping an American working and not supporting our economy.

Second if you are not sure then BUY American.

BONG!!!!


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## beenthere (Oct 11, 2008)

Plumber101 said:


> BONG!!!!


 
Spammers.


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## kenmac (Feb 26, 2009)

Plumber101 said:


> First I would like to thank you for not keeping an American working and not supporting our economy.
> 
> Second if you are not sure then BUY American.
> 
> BONG!!!!


 


What ??


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## yuri (Nov 29, 2008)

Both posts has the same count # 178. Should have increased if it was him?


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## nina01 (Mar 25, 2009)

Plumber 101: I agree. Americans should make it a point to buy "American". I bought an American made home in the United States--and unfortunately the builder (or previous homeowner) chose to purchase a foreign furnace. What was I supposed to say...I'll take the home, but only if you pull out the furnace?


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## kenmac (Feb 26, 2009)

well, Did you perform the checks ?? Just because it shows a code showing vaccum switch doesn't mean it's that switch.. Other things operate or cause that switch to to operate


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## nina01 (Mar 25, 2009)

Fixed. It was the igniter assembly. The pressure switch initially tested fine with the manometer, but after installing the igniter something went wrong. So, I then tested the switch to make certain that the draft inducer was working properly--and it was. When I troubleshooted the control center everything ran fine--the test sequence indicated that the problem wasn't with the control center. To make a long story short, the problem was entirely my fault…I left my husband alone in the basement with the furnace. He was inadvertently switching the hoses to the pressure switch. This is why sometimes the furnace would run fine (during test mode) and then it would stop working. The last time he did this I asked how it was that he could not read the numbers on the meter, but had no problem reading the positive sign on the switch. We then realized what had happened. I feel silly posting this, but perhaps someone will learn from this mistake. Thanks to everyone for all the help.


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## beenthere (Oct 11, 2008)

yuri said:


> Both posts has the same count # 178. Should have increased if it was him?


A spammer posted a link to buy bongs.
Its been deleted.


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## kenmac (Feb 26, 2009)

nina01 said:


> Fixed. It was the igniter assembly. The pressure switch initially tested fine with the manometer, but after installing the igniter something went wrong. So, I then tested the switch to make certain that the draft inducer was working properly--and it was. When I troubleshooted the control center everything ran fine--the test sequence indicated that the problem wasn't with the control center. To make a long story short, the problem was entirely my fault…I left my husband alone in the basement with the furnace. He was inadvertently switching the hoses to the pressure switch. This is why sometimes the furnace would run fine (during test mode) and then it would stop working. The last time he did this I asked how it was that he could not read the numbers on the meter, but had no problem reading the positive sign on the switch. We then realized what had happened. I feel silly posting this, but perhaps someone will learn from this mistake. Thanks to everyone for all the help.


 


Glad to hear you got it fixed:yes:


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