Evcon DGAT075BDF Furnace not working
Posted: Thu Nov 11, 2010 8:53 pm
Hey guys, great site. I have been working on my furnace for a day or two and need some help.
I have an Evcon DGAT075BDF that is in need of help. The AC worked fine but when I went to turn the heater on...no dice. I was getting 3 flashes (Combustion air switch failed to close). I replaced the combustion air switch with a toggle switch to override the switch to test it. I left the "bad" combustion air switch attached to the 2 hoses coming from the combustion blower motor and the other going to the furnace.
Now the furnace will attempt to ignite the 3 times but fails each time. So I started checking the switches and solenoids. I metered the brown wires at the gas valve to see if I was getting the 24v. The ignitor will glow then I get 26.x volts at the gas valve. The furnace actually attempts to light with ~1 sec of flame and then the voltage at the solenoids drops. It drops as if the control board told it to drop due to a bad switch.
I then ohm'd the upper limit switch and the lower limit switch. they are both closed when the furnace voltage is off.
Does anyone have suggestions? I have a new combustion air switch coming my way but that in itself will not fix the problem. Is the control board bad? Does it require a vacuum/pressure source from the hoses?
Any help would be greatly appreciated. I can meter anything y'all ask so that there are objective measurements.
Thanks
I have an Evcon DGAT075BDF that is in need of help. The AC worked fine but when I went to turn the heater on...no dice. I was getting 3 flashes (Combustion air switch failed to close). I replaced the combustion air switch with a toggle switch to override the switch to test it. I left the "bad" combustion air switch attached to the 2 hoses coming from the combustion blower motor and the other going to the furnace.
Now the furnace will attempt to ignite the 3 times but fails each time. So I started checking the switches and solenoids. I metered the brown wires at the gas valve to see if I was getting the 24v. The ignitor will glow then I get 26.x volts at the gas valve. The furnace actually attempts to light with ~1 sec of flame and then the voltage at the solenoids drops. It drops as if the control board told it to drop due to a bad switch.
I then ohm'd the upper limit switch and the lower limit switch. they are both closed when the furnace voltage is off.
Does anyone have suggestions? I have a new combustion air switch coming my way but that in itself will not fix the problem. Is the control board bad? Does it require a vacuum/pressure source from the hoses?
Any help would be greatly appreciated. I can meter anything y'all ask so that there are objective measurements.
Thanks