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bryantfurnacer · Dec 10, 2008, 07:17 PM

Hi,
My 9-year-old Bryant 355MAV shut off after heating for about 15 minutes, even though the house is only about 60 degrees. I've been trying to figure it out all day.
If I turn the furnace off, then back on, it will start up OK, the inducer motor starts running, the burners light up and the blower runs for a good 15 minutes or so.

Then I start seeing an error code in the little LED lights. Most of the time it is 31, but one time it was 32. The whole thing shuts down. It will try to start up again a couple of times, but the ignition won't light the burners. After a couple of tries it quits all together until I turn the furnace power off and start from scratch.

My owner's manual says the 31 means a high pressure switch fault that indicates high pressure switch is closed at call, or in low heat, or fails to close after call, or opens in high heat. And it says to check for plugged condensate drain, water in vent piping, improper pressure switch wiring or pressure switch tubing connections or failed or out of calibration pressure switches.

Water in the vent piping sounded like the most likely candidate, as we just had a big sleet/snow storm yesterday. I went outside and there is definitely moisture around the opening of the vent (exhaust )tube, but the tube is curved, and I can only see in a couple of inches, not sure how to check the elbow.

As far as the condensate drain, I have no idea what this is.

I am not a mechanic, but can do simple fixes. I'm sure I can check the vent pipe if someone has any idea how I can do it, and also check this drain. Beyond that, I'm not sure.

Thanks so much for any help at all. I hate to spend my kids' Christmas money on a repair call unless I really need to.

MarkwithaK · Dec 10, 2008, 08:23 PM

Could be a few different things really. Inducer could be failing, pressure switch can have moisture inside etc etc.

I assume you have a high efficiency furnace?

bryantfurnacer · Dec 10, 2008, 09:20 PM

Hi,
Thanks for the response. Yes, it is a high efficiency.
I turned off the circuit breaker and restarted the whole thing. It ran for about an hour, though the air coming out of the register didn't seem to be as warm as usual. Then it stopped even though the house was not at temperature yet. It has since cycled on and off a couple of times for 10 minutes or so at a time.
So odd.
Something could be failing. The inducer motor seems to be taking several seconds to get up to speed, don't know if that is usual.
I was just outside looking at the exhaust vent and air was blowing out pretty strongly at me. Smelled a little like exhaust air, I guess that is normal.

hvacservicetech_07 · Dec 10, 2008, 09:54 PM

Is there Two pipes outside?

bryantfurnacer · Dec 10, 2008, 09:55 PM

Hi Hvac

hvacservicetech_07 · Dec 10, 2008, 09:56 PM

How's it going?

bryantfurnacer · Dec 10, 2008, 09:58 PM

Oops, Hi HVAC
Yes, 2 pipes
The intake vent also looks clear. That one points down towards the ground (both come out the side of the house around waist high) Hard to see how it could be plugged, but I did look inside it.

I was sitting watching my furnace run. I noticed it ran for a long time, 30 minutes or so, in the green LED mode. Then it speeded up the blower fan and went into the yellow LED mode, which I think is high heat? That seems to be what triggered it to shut down.

I got the 31 or 32 code, sorry forget which, the burners went off, everything turned off, then about 3 minutes later it started up. Still running I think, about 10 minutes later.

bryantfurnacer · Dec 10, 2008, 10:01 PM

House is up to 62 degrees, which is the warmest it has been all day. But the heat coming out of the registers seems to not be as warm as usual.

hvacservicetech_07 · Dec 10, 2008, 10:01 PM

Have you looked at the chart to see what the codes mean?

hvacservicetech_07 · Dec 10, 2008, 10:02 PM

I'm guessing that you're furnace is 2 stage variable speed blower.

bryantfurnacer · Dec 10, 2008, 10:06 PM

Hi,
Yes, the codes 31 and 32 are similar.
My owner's manual says the 31 means a high pressure switch fault that indicates high pressure switch is closed at call, or in low heat, or fails to close after call, or opens in high heat. And it says to check for plugged condensate drain, water in vent piping, improper pressure switch wiring or pressure switch tubing connections or failed or out of calibration pressure switches. 32 is high pressure switch fail.

bryantfurnacer · Dec 10, 2008, 10:07 PM

I'm sorry. I'm getting sleep deprived. 32 is low pressure switch fault. 31 is high pressure

hvacservicetech_07 · Dec 10, 2008, 10:08 PM

Ok,do you see both pressure switches?

bryantfurnacer · Dec 10, 2008, 10:09 PM

The furnace says it is a Bryant plus 90 high efficiency (natural)
Condensing gas furnace

bryantfurnacer · Dec 10, 2008, 10:09 PM

The pressure switches are the twin round pancake like things, I see them.

hvacservicetech_07 · Dec 10, 2008, 10:10 PM

Ok, do you see the rubber tubes on both of them?

hvacservicetech_07 · Dec 10, 2008, 10:14 PM

Locate where the tubes plug into the furnace and remove the tube and try to clean the hole out,you will need a paper clip or something small.

bryantfurnacer · Dec 10, 2008, 10:14 PM

I see a black rubber looking tube that goes into the side of one of them, and a u-shaped rubber tube where one end goes into the front of each of the round pancake things. They have little clamps at the point where the rubber meets the switch.

bryantfurnacer · Dec 10, 2008, 10:15 PM

I take the tube off at just the end that goes into the furnace? I'll go look and see if I can find that. Then I just take a paper clip and clean out the end of the tube, or should I take it off both ends and blow through it?

hvacservicetech_07 · Dec 10, 2008, 10:15 PM

Leave it connected at the pressure switch,remove the tube where it plugs into the header plat on the furnace.