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Intermittent Furnace Operation - Pressure Switch
I have noticed an intermittent issue twice in the past week where my furnace has not been kicking on with a command for heating.
I typically hold my house at 70degF and the past two times this issue has arrised, the thermostat reading has dropped to 63degF before the furnace comes back to life. I have a one stage Coleman 80% efficiency furnace.
Upon first inspecting the furnace, the inducer motor is running and I'm getting three blinks out of the troubleshooting light. This means that the pressure switch did not close or has reopened.
During the past two instances of this issue, the furnace has come back to life after the inducer motor running for 10-15 minutes.
Things I've checked so far...
-I've checked the connections on the pressure switch. All connectors are firmly attached.
-I've checked the pressure switch hose for cracks and don't see any.
-I've removed the end of the pressure switch hose that connects to the inducer fan housing and used a wire to clear any debris that might be blocking the port, but doing this had no impact after I re-attached the hose.
-I've done a rough check of the pressure switch function by lightly sucking on the pressure switch hose, and when I do so, I can hear the pressure switch click closed.
-My water heater shares an exhaust pipe with the furnace, and when the furnace does come back to life, I don't feel much hot air coming out of the natural draft on the water heater. So, for this reason, I don't think I have any major back draft or blockage on the exhaust pipe.
-I've verified that the inducer motor is getting 120VAC
The furnace is running now and the house is back up to temp, but this is something that will likely happen again and I'd like to get ahead of it before it does.
What are your suggestions? Thanks in advance.