coleman furnace dgaa070bdta won't ignite

Old 02-07-18, 01:17 PM
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coleman furnace dgaa070bdta won't ignite

Hi I have a coleman furnace dgaa070bdta that is not igniting. I recently was having problems with this furnace not igniting and got it going however now I'm starting to have the problem again. Last time to get it igniting the furnace had a blinking green light which I later found out meant ignition lockout, so I just replaced the ignitor and took a look at the small blowing fan and somehow it started running again, but a week later I came home and the trailer smelt like gas so I checked the furnace and it was not burning so I tried to turn it back on once all the gas got ventilated out and it would ignite but turned off again and I haven' been able to get it to run again since. I've tried resettng it with the limit switch, inspected the flame sensor and ignitor and cleaned the flame sensor off but it still won't ignite. The light is even solid green so I have no idea what can be wrong now.
Old 02-07-18, 06:21 PM
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Welcome to the forums.

Furnace repair is not willy-nilly. I am very concerned where you said you smelled gas in the trailer. That is not good. The furnace should not be allowing that much un-burned gas to release.

I've tried resettng it with the limit switch

The furnace follows an exact and logical flow.
1) thermostat calls for heat
2) draft inducer starts.
3) pressure switch proves and igniter starts heating
4) in approx 30 seconds the main gas valve opens.
5) flame sensor looks for a flame. If no flame in 7 seconds.... cycle aborts.

The flame sensor has no effect in ignition. It only proves AFTER the burner lights. If the burner lights and runs for a few seconds.... then it's a flame sense issue.

Nothing to check at the igniter..... it glows white hot or it doesn't.

Has this furnace been professionally serviced ? It should be done routinely.

Diagnostic Flash Codes
Steady light on - normal operation.
One flash - ignition failure.
Two flashes - combustion air switch stuck closed.
Three flashes - combustion air switch failed to close.
Four flashes - limit switch open.
Five flashes - gas valve energized with no call for heat.
Rapid flashing - reversed polarity.

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