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Furnace blows cold air intermittently
I have an American Standard high-efficiency 2-stage natural gas furnace, about 5 years old. The furnace is controlled by a single-stage thermostat, so I believe that the W1 and W2 connections on the furnace must be jumpered together.
The furnace seems to work normally except that 2-3 times during the day, it starts to blow out recirculated air, without any heat. This continues for about a half-hour, during which time the house loses about a degree or two of heat. The furnace then turns itself off. After a few minutes, it turns itself on again, and then there IS heat. I would obviously like the keep the house temperature as constant as possible, but I'm not sure if there is a problem with the furnace, or if something just needs adjustment. Obviously, though, it should either be off, or blowing hot air, not recirculating it for a half-hour by itself as the house gets colder. I don't recall this happening in prior seasons.
My thermostat can control temperature swings to within a quarter degree, so that can't be the problem. I'd appreciate any advice anyone more knowledgeable than myself could give me. Thanks in advance.