# Carrier 58PAV070-12 with error code 31



## peterzhang (Oct 27, 2010)

I have a Carrier 58PAV070-12 furnace with a problem. The blower comes on, but it never ignites. It is giving me error code 12 first, then 31. I did some troubleshooting myself but no luck. I tried cleaning up the pressure switch, the rubber tube going to it, I also tried taking the two wires off pressure switch and jumper them together when the inducer motor is running, still no ignition. There doesn't seem to be any air blockage on the unit. Could it be something to do with the ignition heating element? Please help, Thanks much!


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## kenmac (Feb 26, 2009)

There have been several of these as of late.. Look on the back panel of the blower door & see what that code means



http://www.diychatroom.com/f17/carrier-58sxb-furnace-error-code-31-a-82485/


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## peterzhang (Oct 27, 2010)

Thanks for the reply. I already looked into other posts but my situation is different from theirs. My understanding of that code 31 has to do with the venting of the furnace or pressure switch. After google the error code and read other people posts, I did troubleshooting myself as I mentioned earlier, but didn't find anything wrong with those parts. What am I missing here? Anything else I should have checked? The pressure switch seems to be working fine, motor inducer is running, no blockage, filter is clean, any suggestions? Should I check the trap? THANKS!


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## kenmac (Feb 26, 2009)

If that's a 90 % furnace . your secondary heat exchanger may have to be cleaned depending on furnace age. If you have a volt meter. You can start checking to see where you are loosing 24 volts


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## peterzhang (Oct 27, 2010)

So the furnace is about 10 years old. I guess it's not a 90% efficient furnace. I can borrow a volt meter from work, can you please tell me where and how to check for the 24 volts loose please? This question might sound stupid, it's extremely windy here today, do you think the wind could be part of the cause? Thanks,


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## kenmac (Feb 26, 2009)

If it's not vented with PVC plastic. Then it's not 90 %


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## yuri (Nov 29, 2008)

PAVs and WAVs are mids. Check the red reset button on the spill switch which is located on the box where the vent pipe attaches. Switch is inside the furnace and tucked under/beside the box. Wind can sometimes cause them to trip.


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## peterzhang (Oct 27, 2010)

Thanks for above replies. I have another question I don't know if this could contribute to the malfunction of my furnace. So I replaced the mechanical thermostat to a digital thermostat this summer. I didn't test the heat after I installed it. My AC worked fine this summer. Since I'm getting an error code 31 off furnace instead of LED constantly blinking, is that reasonable to say that electronic thermostat is working fine? and my problem must have something to do with the furnace itself? Thanks,


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## kenmac (Feb 26, 2009)

some t.stats have to be set up for the type of heat you have , gas, elec, hp, etc,If you set it up correctly. then the problem is most likely at the furnace


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## peterzhang (Oct 27, 2010)

So I saw an online video talking about measuring the resistance of hot surface ignitor to determine if it is bad or not. I took a multimeter to measure the resistance of pressure switch and hot surface ignitor as shown on the pictures. The pressure switch shows OL and hot surface ignitor shows 66.4 Ohm, am I doing the correct steps here? Is 66.4 Ohm indicating good working condition? Can I apply the same method to measure pressure switch? I'm getting OL on the pressure switch, I want to ask you guys if the pressure switch is broken?
What puzzled me was I bypassed the pressure switch yesterday but my furnace still didn't get turned on, the hot surface ignitor is cold throughout the entire troubleshoot. Thanks much, guys! Waiting online... Please help!


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## peterzhang (Oct 27, 2010)

I just saw a post saying that a good hot surface ignitor will have a resistance of 40 to 90 ohms. I guess the problem is not hot surface ignitor then since the reading I have off the ignitor is within the range. I went ahead and measured the voltage coming from the controller where the cable disconnected from the hot surface ignitor. The voltage reading is 4.298V. Is the controller / board bad?


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## peterzhang (Oct 27, 2010)

any comments? I used the multimeter to measure some connectors on the board, such as 2 circuit IDM connector and 3 circuit PCB connector. I thought I should have a reading of 110V according to the diagram on the cover but I only got 1.68V. I don't know what I'm doing here apparently. I somehow have a feeling that the board could be bad...  Please help!


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## beenthere (Oct 11, 2008)

Pressure switch is checked while the hose is connected to it, and the inducer is running.

Could have a high limit that is tripped due to a dirty coil or air filter.


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## peterzhang (Oct 27, 2010)

Good point, so far I haven't checked the high limit yet. Could I do same step to check the high limit just like how I checked the inginitor? The board seems working to you guys? Thanks,


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## kenmac (Feb 26, 2009)

Check all your limits.. usually, when a limit is open it will bring on the blower motor & it will stay on. Are you getting 24 v on the white wire at the board on call for heat ?


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## peterzhang (Oct 27, 2010)

kenmac, are you referring to the white wire connecting to the hot surface ignitor? I just uploaded a diagram of my furnace model. Can you please point out to me which white wire I'm supposed to check for 24V? Another question about checking the limit, this might sound dumb, how do I check the limit, using voltmeter to check the voltage or just physically see if any damage? I really appreciate all of you guys help here.


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## The O (Oct 28, 2010)

peterzhang said:


> kenmac, are you referring to the white wire connecting to the hot surface ignitor? I just uploaded a diagram of my furnace model. Can you please point out to me which white wire I'm supposed to check for 24V? Another question about checking the limit, this might sound dumb, how do I check the limit, using voltmeter to check the voltage or just physically see if any damage? I really appreciate all of you guys help here.


You can measure the resistance (ohms) across the limit switch terminals. You should get less than 1 ohms. You may want to hook everything back up and cycle your unit. Pressure switch sounds suspect. Put your meter leads on the terminals (with the wires disconnected) and you should show OL with no call for heat, inducer motor off. Upon call for heat, with inducer running, you should read less than 1 ohms resistance.


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## kenmac (Feb 26, 2009)

He said he by passed the ps & it still wouldn'r start up. That should eliminate the ps. I'm talking about the white wire at the control board. On call for heat the w is powered from the t.stat.. At the limits just check for 24v


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## The O (Oct 28, 2010)

kenmac said:


> He said he by passed the ps & it still wouldn'r start up. That should eliminate the ps. I'm talking about the white wire at the control board. On call for heat the w is powered from the t.stat.. At the limits just check for 24v


If he bypassed the pressure switch while it was operating for some time it was probably already in alarm. If he bypassed it before the inducer energized then it would of also went in alarm. The"white" wire is getting energized or else the inducer motor would not initiate it's cycle


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## peterzhang (Oct 27, 2010)

Here are steps I did when I bypassed the pressure switch
1) shut the power off
2) removed the two wires connected to pressure switch
3) used a safety pin and jumpered two wires together
4) turn the power back on
5) I got error code 12 initially, 90 seconds later, inducer motor was on, error code became 31, hot surface ignitor was cold, I didn't leave the furnace on for very long, I just turned it off immediately. 

I'll measure that white wire as knmac suggested to see what I get tonight. I'm also planning to take off some parts, i.e. pressure switch, ignitor and put them in my neighbor's furnace to see if they are working or not. All of our houses were built by the same builder at same time, so all our furnaces are same. I hope I can figure it out soon before temperature gets too cold. 

So you guys don't think the board is the problem in my case? Thanks much for all the replies. Let me know if you guys think of something else I shall check.


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## The O (Oct 28, 2010)

When you bypass your switch before the inducer is coming on your board will go into alarm. The right way to test it is to disconnect your wires and 5 seconds into inducer operation, jump the wires together. THEN your ignitor will glow and burner will fire up. It is very important that these switches don't get jumped out but only for troubleshooting. This is why it won't operate by someone leaving jumpers on it. The board is smart, needs to read an open switch with inducer off then read close when it is supposed to be on


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## peterzhang (Oct 27, 2010)

guys, thank you so so much for all your helps here. My furnace is working now. I noticed the high limit switch got triggered, I reset it, and tried again, it's working now. so what could cause the limit switch trigger? wind? Thanks,


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