Furnace Code 31

[ThePenIsMightier]

I've got the old 3 blinks, plus one long blink which seems to translate to Code 31 on my Carrier Infinity. This must be a very minor issue because it usually fixes itself before I can do anything, but I'm going to ask here anyway. According to the manual, this means:

Code 31: HIGH-HEAT PRESSURE SWITCH OR RELAY DID NOT CLOSE, OR RE-OPENED. indicates the high-heat pressure switch input failed to close or opened during high-heat. Control relay may be defective or gas valve is miswired. Refer to status code # 32.

Code 32: LOW-HEAT PRESSURE SWITCH DID NOT CLOSE, OR REOPENED. Indicates the low-heat pressure switch input failed to close on a call for low-heat, or opened during low-heat. If opens during 5 minutes after ignition the next heating cycle will be restricted to high-heat. Check for: proper vent sizing, excessive wind, plugged condensate drain, low inlet gas pressure (of LGPS used), restricted combustion air supply, improper pressure switch wiring, water in vent piping or possible sagging pipe, disconnected or obstructed pressure tubing, failed or "out of calibration" pressure switches.


So, what's the most likely fix it checks for this?

Help is greatly appreciated!

[jeffh]

As always, ensure your filter isn’t too dirty.
As for issues I’d look at checking into, it would be the following:
-water in vent piping and vent fan housing.
-water in rubber tubing coming from pressure switches
-disconnected or obstructed pressure tubing
-failed or "out of calibration" pressure switches

[Darell_n]

There seems to be an industry wide problem with making pressure switches that actually work. It’s one of the manufacturer’s money makers. My guess is there’s an updated switch to address the problem and shockingly, its 6 versions newer than what you have. A very loose guess, mind you.

[ThePenIsMightier]

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There seems to be an industry wide problem with making pressure switches that actually work. It’s one of the manufacturer’s money makers. My guess is there’s an updated switch to address the problem and shockingly, its 6 versions newer than what you have. A very loose guess, mind you.

Thanks, I'll look into that further.
I think perhaps the most important symptom is that it fixes itself and has been for years. I've maybe never noticed an actual problem with the furnace not providing adequate heat. I've only stumbled onto seeing the blinking lights while I'm down there. By the time I finished this post, the lights stopped blinking.

It's definitely not a clogged filter, as I've got the cheapest, shittiest one in there still from last month's cold. I'm going to finally go to that store you've recommended and buy a decent MERV-8 or higher now that spring is here.

That "wind" mentioned under the code-32 description could certainly be it because it always goes away, although it wasn't windy yesterday morning and I haven't seen a correlation between wind and this problem.

[Darell_n]

When the code comes up it will switch back to low fire while heating. There is normally a set number of attempts for high heat before it locks out so 1 successful attempt clears the code.

[ThePenIsMightier]

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When the code comes up it will switch back to low fire while heating. There is normally a set number of attempts for high heat before it locks out so 1 successful attempt clears the code.

Makes sense, I guess.
Do you have a rough guess on pressure switch cost?

[vengie]

Just a heads up, I just had the same issue on my furnace, bought a pressure switch, but before I installed it I decided to clean the flame sensor... Furnace fired right up and hasn't had an issue since..

Returned the pressure switch.

[Cash Money Hoes]

Sounds like plugged condensate trap. If water sounds like it is sloshing around when the inducer comes on, it is likely clogged condensate trap. Water will drain out of the condensate tubes when you remove the trap. It is that white plastic thing with black drain tubes going in and out