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czombos47 · Jan 30, 2006, 10:48 AM

Ok. I can turn the thermostat to 72 and it will stay on 64 with the fan blowing constant. Burners aren't firing. On the control board for the furnace, there is a trouble shooting light that blinks to tell you what is wrong. It blinks four times which indicates an "Open Limit Switch", and it tells to check the "main limit open", or the aux limit open". Well, where are those and is this going to b tough and expensive?

labman · Jan 30, 2006, 11:00 AM

Maybe an easy one I can solve. The limit switches will be in the heat exchanger. They let the control board know something is wrong because it is too cold or too hot. Maybe an oval thing with 2-3 wires going back to the control board. Pull them out and take to an electrical or heating supply and they should have new ones.

czombos47 · Jan 30, 2006, 11:12 AM

Is there any site I can go to that would have the discription or loctation of the heat exchanger, or the oval part with the limit switc:confused: :confused: he's located?

labman · Jan 30, 2006, 11:24 AM

You might find a diagram on the Goodman site. Usually you can see the blower and control board when you open the panel to change air filters. The blower pulls air in the center and out the side away from the filters into the heat exchanger.

wheatnbarley24 · Jan 30, 2006, 05:46 PM

You might want to make sure your filter and cooling coils are clean also your exchangers and flu pipe. Lack of air flow is the main cause of a limit tripping

letmetellu · Jan 30, 2006, 07:22 PM

If you furnace is an upflow model the main limit should be on the furnace just about the bburners. It si a flat sheet of micarda like material about one inch by one and a half inch with two wires attached. You can short across the to contacts where the wires are connected and if the blower stops running then the limit is bad. If it continues to run there is another check point in the same location. On one of the wires there is a little firecraker type fuse that is to protect if the flame rolls out the front of the furnaces burners. If you will short out the wire on either side of the fuse and the blower stops then this is the problem. This is the way Carrier furnaces are wired and I am sure that Goodman have something similar.

RIBBS4 · Jan 30, 2006, 07:53 PM

Originally Posted by czombos47

Ok. I can turn the thermostat to 72 and it will stay on 64 with the fan blowing constant. Burners aren't firing. On the control board for the furnace, there is a trouble shooting light that blinks to tell you what is wrong. It blinks four times which indicates an "Open Limit Switch", and it tells to check the "main limit open", or the aux limit open". Well, where are those and is this gonna b tough and expensive?

You will find the limit switch near the burners... it has two wires
Going to it. There should be a red button sticking up... just press
It in... there may also be others like in the burner cabinet.. or it
Could be a bad fan relay.. that is a also a switch with two and
Sometimes three wires going to it. It is mounted on the wall on the burner cabinet. It is about 2" BY 3". Try jumping those wire out
By putting a wire between the two wires.. if your burner lights,
There is your problem. Get a new one from any goodman supplier
Asap. Good luck

rescher · Dec 6, 2010, 09:46 AM

I have a goodman, GMP Series Furnace and it is only clicking. Any suggestions