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Phil
Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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We have a goodman furnace, approximately 2008. We cut the

Customer Question

Customer: ***** ***** We have a goodman furnace, approximately 2008. We cut the main power to the house today for another reason and when we turned it back on, the furnace started blowing cold air. We are getting 4 led flash indicating a limit switch open issue. There is not a manual reset on this switch from what I can see.
JA: Thanks. Can you give me any more details about your issue?
Customer: That pretty much covers it. I have tried resetting the breaker to just the furnace to see if that would reset the LED indicators but as soon as the furnace if turned back on either via the thermostat or the breaker, it flashes the four red LEDs well, they are actually more of an orange
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Submitted: 12 months ago.
Category: HVAC
Expert:  airheatman replied 12 months ago.

Most Goodman furnaces will have manual reset limits just above burners, See images below . Not sue why turning power off and back on would cause this though.Lets check these any way and we will go from here. Also let me know if you have a meter for troubleshooting.

http://i.imgur.com/CGkB9sa.jpg

Customer: replied 12 months ago.
There is a manual on off switch that I can flip right above the burners. I have turned this off and back on. I have turned the power off to the furnace at the furnace and at the breaker and also tried turning the heat off an on at the thermostat. Unfortunately, no meter.
Expert:  airheatman replied 12 months ago.

Look just above burners on inside panel and give me furnace model.Also try killing power at breaker and then turning back on to see if board will reset.

Customer: replied 12 months ago.
I've already killed the power at the breaker two or three times. Does it matter if the thermostat is set to off or on when I reset at the breaker. I have it off right now so it doesnt blow cold air. I took a few pictures that I will be sending in a second. Model: GCH90904CXAB
Customer: replied 12 months ago.
pics
Expert:  airheatman replied 12 months ago.

OK the switch in picture one just turns gas valve on and off. Does not kill power to furnace.The resettable limits are shown here.Button pushes in to reset

Expert:  airheatman replied 12 months ago.

Below is a diagram showing all the limits on the furnace. Since you do not have a meter, you can bypass one at a time by unplugging and connecting the two wires together to see if one is actually open.

Customer: replied 12 months ago.
I reset the bottom two but they did not need reset. I tried bypassing all three and am still getting the same result.
Expert:  airheatman replied 12 months ago.

OK if all limits are closed but board says open limit, board has failed.Did you have a power surge or anything earlier?

Customer: replied 12 months ago.
Just killed power to the breaker when trying to locate the correct breaker for our dining room.
Expert:  airheatman replied 12 months ago.

That really should not have caused an issue with furnace by nay means but we are definitely getting a false code if it is saying limits are open and we prove they are not. Possibly a coincidence.