Coleman furnace #dgaa090bdta flashing 4 code

That's how it should work .Your furnace will cycle on and off to reach set point .
You don't have to troubleshoot the thermostat. The reason why your furnace cycle is once the heat exchanger get to a certain temperature the board will shut it off, fan would still work to cool heat exchanger down then once cool down furnace will fire up again .

IF YOU LOST POWER WHEN FURNACE WAS RUNNING IT TRIPPED ROLLOUT SWITCHES AND POSSIBLY THE HIGH LIMIT . IN CENTER OF ROLLOUT SWITCHES IS A LITTLE RED BUTTON THAT YOU RESET . YOU CAN ALSO TRY FINDING HIGH LIMIT WITH POWER SHUT OFF TO FURNACE PULL BOTH WIRES OFF HIGH LIMIT AND USE PAPER CLIP TO JUMP BETWEEN THE TWO WIRES MAKE SURE YOU DONT SHORT OUT AGAINST ANY METAL WHEN YOU TURN BACK ON IF IT WORKS YOU NEED A NEW HIGH LIMIT SWITCH.

Limit switches are safeties and require a manual reset. They are also a Normally Closed contact. A hi temp. thermostat operates on its own. If you are sure it is a limit, find the red little button and listen for it to click. Sometimes they push pretty hard.

Blower motor is bad or going bad

Is this a blend air system? If so, there is an upper & lower control board that communicate to each other, and if the exhaust fan on the roof is out, it will give you intermittent issues. The fan mixes or blends outside air with the return of the air handler, & duals to pressurize the attic. These were installed due to mobile homes built too air tight. Without this fan, your roofing shingles will curl, and your roof decking will bow prematurely.

That's a coleman brand furnace and the four blinks of the green LED light indicate that the lower limit switch is currently open which would indicate an overheating issue. This would cause the gas valve to not open and thus no flame and no heat. Likely, the switch is just bad and needs to be replaced. Here is a source for the switch: http://www.hvacpartstore.com/2409.html . The switch is located right next to the electronics control panel un the upper section of the furnace. You can try turning off the power and taking the switch out and tap on it a few time or try to flex the snap sensor a little bit on the back side. That might get it working temporarily until you can get a new on. Just don't try to bypass the switch or modify it all since it is very necessary for saftey.

Hey, nofarmark91

Turn the Coleman furnace system switch to the "Off" position on the electric service panel.

Locate the manual reset switch near the left side of your furnace blower. Your Coleman furnace has an upper limit switch for manual reset and a lower limit switch for automatic reset.

Press the reset button, which you will find in the middle of the limit switch. Use this manual reset button when the furnace burner will not operate. (See Reference 1 pg 4 "The Furnace Controls and their Function/Important" & Reference 4 # 3)

Turn the system switch to the "On" position.

Good Luck

i hope the heater doesnt come on when a limit switch is open,you really have problems. so a limit is telling you that your furnace it over heating. first check filter and heat vents and returns they must be clean and open. closing heat vent or blocked returns will cause over heating. after chacking this look at firing rate. furnace could be overfired. you would need a "u" gauge to check manifold pressure. your name plate will tell you what this should be. find the tap on the burner manifold or outlet of gas valve. fire furnace and see what it is. 3.5"wc for nat and 10" wc for propane maybe.

If its a High Eff. Furnace, does it have a two pipe or
single pipe system?

have someone check the gas presure most likely too high no more than 11