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M Oglesby
M Oglesby, HVAC Technician
Category: HVAC
Satisfied Customers: 2038
Experience:  Universally Certified HVACR Technician
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I have a Goodman Furnace Model # GMPN 120-5 Rev B SN XXXXXXXXXX The

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I have a Goodman Furnace Model # XXXXX 120-5 Rev B
SN XXXXXXXXXX

The blower motor runs even with the thermostat turned off. I replaced the thermostat.
The status light on the circuit board flashed 4 short flashes the off, then repeats 4 short flashes
what is my problem

M Oglesby :

Remove the furnace door panels and look on the back of them to find out what the 4 flash troubleshooting LED code is indicating.

M Oglesby :

Let me know what you find.

JACUSTOMER-hr8sczux- :

Open limit switch

M Oglesby :

There are two kinds of limit switches.

M Oglesby :

The first kind that we will try to locate are called manual reset rollout limit switches.

M Oglesby :

They are small round metal looking devices with two wires attached to them and a little button on the back of them. They are usually located inside the furnace cabinet around the burner tray. Locate them and let me know when you find them. Remember there may be more than one.

JACUSTOMER-hr8sczux- :

I have found 2, they are a button shaped item and are connected together

M Oglesby :

Press the little buttons in that is on the back of them.

M Oglesby :

Let me know when you finish.

JACUSTOMER-hr8sczux- :

ok, I pressed the button. it didnt stay in

M Oglesby :

When is the last time that you changed your filter?

M Oglesby :

Did you press the button in on both of them?

JACUSTOMER-hr8sczux- :

the filter is new. I pressed the butto on all four (found tw more

M Oglesby :

Did they all go in?

JACUSTOMER-hr8sczux- :

they went in but came back to original position

M Oglesby :

Try to turn the furnace on.

M Oglesby :

Let me know what happens.

JACUSTOMER-hr8sczux- :

I tried but still nothing

M Oglesby :

Lets try to locate the main limit switch.

JACUSTOMER-hr8sczux- :

ok

M Oglesby :

It is a rectangular device that has two wires attached to it. It sits inside the furnace cabinet on the back panel wall. Locate it and let me know when you find it.

JACUSTOMER-hr8sczux- :

I think I have located it. The item I located appears to be about 3" long and about 1.5" wide. It is black and looks to be a non metallic substance . It has two red wires attached and is fastened to the furnace with 2 screws

M Oglesby :

That is it.

M Oglesby :

Remove the two wires from it and attach them together very good metal to metal.

M Oglesby :

Once they are attached, attempt to call for heat.

M Oglesby :

Let me know what happens.

JACUSTOMER-hr8sczux- :

OK.. It worked! the furnace ignited

JACUSTOMER-hr8sczux- :

Now I guess I have to replace that switch

M Oglesby :

Yes you will have to replace the Main Limit Switch.

M Oglesby :

Please hit ACCEPT if you are satisfied with this answer. If not, I will continue to assist you. Thanks! Bonuses and positive feedback are very very much appreciated!! Happy Holidays!!

JACUSTOMER-hr8sczux- :

Thank you

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