dmadams327
Dec 29, 2009, 02:18 PM
The diagnostic light blinks twice on Coleman Evcon #DGAHO56BBSA 5600BTU natural gas forced air out bottom Mobile home heater. 2 blinks is supposed to be "combustion air switch stuck closed" which is called a pressure switch in the part manual. When I restart the furnace cylce and place suction on the upper tube of the pressure switch (with my mouth) the furnace cycles through and the burner fires up and heater operates as normal until it shuts off about 20 minutes less or more later. The 1st couple times I tried this technique for a manual start I wanted it to run throughout the cold night so that I would not have to get up and restart it, so I turned the thermostat to max and it worked all night until the warmth of the day, but now it stops heating after a relatively short cycle which makes me also wonder about the thermostat. A repairman came out and checked the electric current flow and the pressure and when he recycled the system it worked without help but turned off after he left. He commented the pressure measurement (suction?) seemed low but thought that pressure was not the problem and the problem was either replacing the pressure switch, or the circuit board that had some dark brown areas from apparent over heating, for which he wanted around $800 that I cannot afford. So I tried the 'sucking' manual start method that, now does not work through the night. I guess I will start with replacing the thermostat, then move to the pressure switch, then move to the circuit board? But am concerned that the problem is something to do with the pressure generated by the gas burner?