Troubleshooting Carrier Furnace Code 31 - HVAC - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 02-19-2013, 11:11 AM   #1
Newbie
 
Join Date: Feb 2013
Posts: 7
Rewards Points: 10
Default

Troubleshooting Carrier Furnace code 31


Hi. I have a Carrier Model 58MXA08-12 with Serial number 3496A06075. The furnace has been set to 68 degrees. The last two mornings the temp was 66 in the morning and the thermostat from 68 did not turn the furnace on. I checked for codes, and it was flashing 31. Both times I have turned the power off and then back on (breaker or switch on the furnace), and it has started fine. That obviously isn't fixing the problem though.

I have done some looking on-line. Based on that I have looked at venting and filters. I have not found any venting issues (though I need to get on the roof when weather and work permit), and filters are good. Will call for repair if necessary, but I would like to rule out the simple problems (and perhaps a not-so-simple problem or two) myself before calling.

Thanks for any assistance.

Advertisement

oldducts is offline   Reply With Quote
Old 02-19-2013, 12:27 PM   #2
how
Member
 
Join Date: Feb 2011
Location: Vancouver BC
Posts: 1,545
Rewards Points: 606
Default

Troubleshooting Carrier Furnace code 31


31 = pressure switch. Checking for a debris build up inside the ID assy port that the hose from the PS is attached to, is a more common DIY fix. Make sure nothing is blocking your vent exhaust or intake.
Beyond that it can be 30 or more other possibilities.
A manometer check against the rating on the PS tells if the problem is with a faulty Pressure switch or the furnace.

Advertisement

how is offline   Reply With Quote
Old 02-19-2013, 08:23 PM   #3
Newbie
 
Join Date: Feb 2013
Posts: 7
Rewards Points: 10
Default

Troubleshooting Carrier Furnace code 31


Nothing blocking the vent exhaust or intake. Not quite sure where you are suggesting I check for debris - happy to check if I can figure it out though. (I have to admit, I am not sure where the PS is.)

I did check the condensate trap, and that seems to be blocked. (I disconnected the output hose from the trap, and it was dry, but I disconnected the input (largest of the three hoses attached to it) and quite a bit of water drained out.) Assuming that indicates that it is blocked, what is the best way to clean out the condensate trap? Is there a trick to removing it?

Thanks for any further assistance. Hoping for heat tonight....
oldducts is offline   Reply With Quote
Old 02-19-2013, 08:57 PM   #4
Newbie
 
Join Date: Feb 2013
Posts: 7
Rewards Points: 10
Default

Troubleshooting Carrier Furnace code 31


Okay, I was able to remove the condensate trap. It was definitely clogged. ran some water through and shook it a bit until a bunch of "debris" came out then water ran through it cleanly. Have put it back together, and it is running so I will see what happens.

Will be back if this didn't work. In the meantime, let me know if there is anything else I should check.

Thanks.

Chris
oldducts is offline   Reply With Quote
Old 02-19-2013, 10:22 PM   #5
Roofmaster
 
Join Date: Oct 2012
Location: Maryland
Posts: 3,669
Rewards Points: 2,096
Default

Troubleshooting Carrier Furnace code 31


Your trap and the lines to it are probably full of crap.

Take off the hose clamps remove the hoses to the trap and clean out the hoses by submerging them and trap in sudsy bleach and warm water and clean everything well. Be very careful removing the hoses that you don't break off the plastic nipples. Suck out the secondary HE drain with your shop vac. When you put the trap back, prime it with water and a little bleach.

Make sure your vacuum hoses are not cracked or stopped up also blow them clear with compressed air. Make sure the hose barbs on pressure switch are not clogged. Also clean electrical connections.
__________________
" A lot of men build things, and a lot of things fall down "

jagans is offline   Reply With Quote
Old 02-20-2013, 08:54 AM   #6
Newbie
 
Join Date: Feb 2013
Posts: 7
Rewards Points: 10
Default

Troubleshooting Carrier Furnace code 31


Possibly a stupid question except that I am not sure of the answer. Water from the inducer hose drains through the condensate trap just fine, but water from the collector box hose does not drain. Should it?

Am soaking parts now and will be checking vacuum hoses.

Thanks for the help.
oldducts is offline   Reply With Quote
Old 02-20-2013, 09:25 AM   #7
Newbie
 
Join Date: Feb 2013
Posts: 7
Rewards Points: 10
Default

Troubleshooting Carrier Furnace code 31


Update:

1) Last night after work, I got home to code 31. I removed the condensate trap, and ran water through it until I got water running freely from the inducer input to the output. Reinstalled, set up the drain to drain to a bucket so I could verify it was draining, turned it on, and it ran fine for several hours.

2) At some point during the night, it threw the code 31 again. The bucket did confirm that condensate was draining.

3) Removed the trap again this morning. The hose from the inducer to the trap had water backed up. Removed the trap and soaked it. Did not appear to remove debris, but it does drain (from the inducer input - not from the collector box input if that matters). All vacuum hoses to the PS are clear removed and reinstalled the electrical connections a few times. Was able to elicit a click on the PS with gentle blowing into vacuum tube. As far as I can tell the barbs on the PS are clear.

4) put it back together, and it starts fine. Inducer motor works fine, burners fire, blower comes on. I now expect that it will work for some period of time and then stop.

Any further suggestions?

I am learning a lot - thanks.
oldducts is offline   Reply With Quote
Old 02-20-2013, 09:47 AM   #8
Roofmaster
 
Join Date: Oct 2012
Location: Maryland
Posts: 3,669
Rewards Points: 2,096
Default

Troubleshooting Carrier Furnace code 31


Most definately. The black plastic collector box covers the end of the secondary heat exchanger. You may have to remove the inducer motor or better yet the collector box to really get the insides clean. You may be looking at a secondary heat exchanger that has been recalled by Carrier. If it is coated with polyester paint, the ends of the secondary heat exchanger tubes start to peel and rust, and the stuff clogs up your condensate drainage.

The problem comes when you try to remove the collector box. The sealant they used hardens and it is very easy to break the box in the removal process, but it can be done. I sprayed mine with WD-40 several times and it seemed to break down the sealant to some degree, I then removed the box by applying continuous gentle pressure with two wonder bars.

First try to remove the inducer fan, this will give you some limited access to the end of the secondary HE through a half moon shaped hole. AGain spray and apply gentle pressure till it starts to give. Spread the load with a metal plate behind the fulcrum.

You can get a plastic toilet cleaning brush in there by reshaping it, and you can vacuum out the crap with a shop vac with some creative tubing.

I ended up taking off my collector box which I cracked, I wire wheeled the ends of the tubes, and resealed around the ends of the tubes with GE fast cure clear silicone. My HE leaked, and this solved it.

I patched my collector box with fiberglass drywall tape bedded in the aforementioned silicone, and patched the outside with pressure sensitive EPDM Tape. All Worked great. HE no longer leaks, condensate drains well.

A clogged condensate line fried my board, which has been replaced along with my HSI and a pressure switch. Furnace now runs great.

I like Carrier a lot, but that polyester coating was dumb. SS would have been better, and less expensive in the long run.
__________________
" A lot of men build things, and a lot of things fall down "

jagans is offline   Reply With Quote
The Following User Says Thank You to jagans For This Useful Post:
how (02-20-2013)
Old 02-20-2013, 11:29 AM   #9
Newbie
 
Join Date: Feb 2013
Posts: 7
Rewards Points: 10
Default

Troubleshooting Carrier Furnace code 31


Thanks! I think I understand the mechanics of what is happening. The condensate trap is still clogged an is not letting the collector box drain. So I have come along twice and drained the collector box. That works fine until too much condensate builds up again. Is there any trick for more thoroughly cleaning the condensate trap or might it need to be replaced assuming I can't get water to flow from collector box through the trap.

I will take a look at the collector box and secondary heat exchanger. My understanding from the serial number is that this unit was made in 1996 so I believe it would be eligible for replacement. Will see about removing collector box. Don't want to break it. Will remove inducer fan and see what I see.

Thanks for any further info on the collector box and condensate drain.
oldducts is offline   Reply With Quote
Old 02-20-2013, 06:58 PM   #10
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,414
Rewards Points: 4,480
Default

Troubleshooting Carrier Furnace code 31


Hot water and Ivory dish soap. Shake vigorously. Let set, repeat. Dump out dirty soapy water, flush the trap with clean water in all directions. Put it back in furnace and run furnace.

Are you on natural gas, or LP.
beenthere is offline   Reply With Quote
Old 02-20-2013, 10:22 PM   #11
Roofmaster
 
Join Date: Oct 2012
Location: Maryland
Posts: 3,669
Rewards Points: 2,096
Default

Troubleshooting Carrier Furnace code 31


Well there was a class action suit on the secondary HE. Mine was made in 1993, and I qualified for $124.00 as it was pro-rated. I said Wowee what a deal! and proceeded to fix mine myself. The cost to replace the HE at this stage of the game just is not worth it.

As with most class action suits, the attorneys take all the meat, and leave the plaintiffs with the bleached bones. The end result is Carrier raises the price of their parts to make up for the loss.

What do you call 2,000,000 dead Lawyers? A good start.
__________________
" A lot of men build things, and a lot of things fall down "

jagans is offline   Reply With Quote
Old 02-20-2013, 10:26 PM   #12
Roofmaster
 
Join Date: Oct 2012
Location: Maryland
Posts: 3,669
Rewards Points: 2,096
Default

Troubleshooting Carrier Furnace code 31


Yeah you need to really clean the trap. Just remove the two hoses, take out one screw in the bracket and remove it. I used dish soap, TSP, and Bleach in warm water, but I guess Ivory will work too. I needed more horsepower.
__________________
" A lot of men build things, and a lot of things fall down "

jagans is offline   Reply With Quote
Old 02-21-2013, 07:34 PM   #13
Newbie
 
Join Date: Feb 2013
Posts: 7
Rewards Points: 10
Default

Troubleshooting Carrier Furnace code 31


Thanks everyone. Soak, shake, rinse, repeat finally worked.

I have been good for over 24 hours now. Of course I haven't fixed the underlying problem. I elected to quit while I am ahead and not try to get at the collector box or secondary HE. I will see how long it is until it clogs again.

beenthere - the system is natural gas.

jagans - interesting information on the prorating of payment on the HE.

very cool to have a better understanding of how the furnace works.

Best,

Chris

Advertisement

oldducts is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Carrier Infinity 58MVb Code 13 Earl B HVAC 4 10-19-2011 09:44 AM
carrier furnace code 16 on the damper control module sanfcarolyn HVAC 0 06-21-2011 07:46 PM
Carrier Error Code 33 russell124 HVAC 4 12-04-2010 08:19 PM
Carrier Furnace LED Code 34 and 14 sherjack HVAC 20 11-01-2009 09:45 AM




Top of Page | View New Posts