A very common problem with high efficiency gas furnaces that have a pressure switch is the accumulation of moisture (condensation of water vapors) near the inducer motor housing. This can block your pressure switch and that fools the heater into thinking there is a problem with the exhaust pressure. It results in error code 31 on my Bryant Plus 90 gas furnace. This error code indicates many possible issues. One reason maybe a stuck Pressure Switch – if you are lucky, just tap it and it will work again for a while (see here for more info on the stuck and replacement pressure switches:
The problem in this video here, hoever, is not due to a pressure switch failure. The issue is that water condensates inside the exhaust pipe and drips back down into the fan housing. About a quart of water accumulates every few hours on very cold days. The cause is that the exhaust pipe is not well insulated. There is a collector box where the water drains to and from there, into a drain. That box gets clogged over time and needs to be cleaned. Before I found out about that clogged box, to make the system work (it shuts off when error 31 happens), I had to disconnect the tube from the fan to the pressure switch and drain all the water. That needed to be done every couple of hours!
The repair is simple, conceptually: find the clogged area and unclog it :)
Thanks for watching and hope this helps you on a cold day!
I also found helpful this video: