I have been lurking on this forum and have found answers to my questions until now. I have a Coleman model # DGAA090BDTA that we turned on for heat a couple of weeks ago. I got the 3 blinks that indicate that the combustion air switch failed to close. I purchased-thru the catalog part # 024-27666-001-the switch and installed it. Turned the furnace on and got the same 3 blinks. I can induce and hold vacuum on the - side of the switch and the furnace will fire and run. When I release the vacuum the furnace shuts off and I get the same 3 blinks as error code. Any help would be appreciated.