Bryant Furnace Pressure Switch Problem
I have a problem with my home furnace I'm hoping someone can help me with. It's a Bryant 340MAV 036080, about 12 years old. It's not given any problems since I've been here until now.
We had a large snow storm a couple days ago, and when blowing the slow I inadvertently covered the inlet pipe. No big deal I figured, and cleared out the area around it, and made sure it wasn't plugged. Later that day I realized there was no warm air coming.
I check the furnace and had a code 31, indicating a pressure switch malfunction. I figured some snow got into the pipe, so I put a space heater in the area over night. No luck the next morning. The pressure switch is a differential switch, and in playing I realized if I disconnected the end going to the combustion chamber plenum, it would switch. So my furnace ran lots and I was hoping if it was snow related it would clear itself out. But no luck. I hook up the tube to the plenum the differential pressure drops just enough to open the switch. I check the pressure with a manometer and I have about 1"WC, and I think I should be closer to 1.8 or 2" WC.
Anyone have any suggestions on what might be wrong? Any good ideas on how to check the entire length of the exhaust piping? The only thing I'm left thinking is that something is partially blocking that.