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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8327
Experience:  Furnace, A/C and heat pump specialist.
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Goodman furnace with 4 blinks on red light. I reset the

Customer Question

Goodman furnace with 4 blinks on red light. I reset the limits on both sides and it works for a few minutes blowing heat and then the error code/ 4 blinking red lights return! Any suggestions?
JA: Did you double-check the thermostat's settings? And what about the filters?
Customer: New filter and the thermostat settings are fine. Also cleaned hoses and confirmed they were free of water and debris. Been having this problem for several years. I put a cap on the exhaust pipe on the roof. It used to get clogged with acorns and trash, so Ive been here done this before. I high hope its not bad limit switches because they are on the sides and VERY hard to get to. Scrape arms resetting them.
JA: Do you plan on doing the work yourself?
Customer: Yes, Im not HVAC certified but I am an industrial maintenance electrician and found and fixed this problem before many times but I have never had to replace the switches
JA: Anything else we should know to help you best?
Customer: is there anyway to change the switches on the sides without cutting a hole in the wall on both sides or pulling the entire unit out?
Submitted: 10 months ago.
Category: HVAC
Expert:  airheatman replied 10 months ago.

Are you having to manually reset the limits or does it auto reset?

Expert:  airheatman replied 10 months ago.

Can you give me complete model from inside furnace in burner compartment so I can provide guidance with this specific unit.Model will be on a label just above burners on right or left inside panel

Customer: replied 10 months ago.
manually reset the limits, which I have done several times this time and multiple different times over the last 4-5 years
Expert:  airheatman replied 10 months ago.

Ok what is model on unit and are these the ones right beside or above burners (flame roll outs? If so is the flame coming out of the heat chamber to trip them when blower comes on?

Customer: replied 10 months ago.
I am not at the house at this time where the furnace is located. It is at my girlfriends house that is used to live with. The furnace went out Thanksgiving morning while she was getting ready to come to my house so I don't have model number and specifics right now. I am loading up tools, Fluke meter and looking for help before I go attack this furnace again. I have even talked my girlfriend on how to reset the limits and make the 4 red blinking lights go away and run properly. She did a few times yesterday and the furnace reset and came back on blowing air. Filter clean, hoses cleaned, and limits manually reset but they keep tripping! I am not sure what else to do except replace the limit switches
Customer: replied 10 months ago.
The limits are on the sides when you face the circuit board. It will be a few hours before I gather up tools and get to her house.
Expert:  airheatman replied 10 months ago.

OK first thing is to watch the burners and see if the flame is floating out of the heat exchanger causing the rollout limits to trip.If it is, the problem is much more serious than just limits.You have a bad heat exchanger.

If we can determine flame is fine then you will need to replace limits.If the limits are so close to sides that you can not get to them, we should be able to remove the burner assembly from the furnace by taking a few screws loose.

I will need model on unit to give you specific detailed instructions on removing .

Customer: replied 10 months ago.
you are saying I can replace the 2 limits, one on each side by removing the burner assembly out the front. These limits are on left and right side of blower which is above the burners. They have been tripping on occasion either left, right or both since the unit was about 2 years old. Its about 6-7 years old now.
Customer: replied 10 months ago.
Unit is in furnace closet with about 3 inches on each sides and they can't be accessed unless I cut a whole on both sides
Expert:  airheatman replied 10 months ago.

I will need the model to pull a manual to identify the exact location of the switches and give you detailed instructions.Nothing on te Goodman furnace should require removing the furnace or cutting any holes.

Do you have internet access on site when you get there?

Customer: replied 10 months ago.
I have internet access there. How long will you be online today? I will log back on with the model # after I get there. Can you send an email to her with a link so we can pick up where we left off? Her email is***@******.***
Expert:  airheatman replied 10 months ago.

Sorry I got called out of the office.Did you get the model number?