I have a goodman GMP 125-5 furnace. I have

It does sound like a bad blower motor but the power that is supplied to the motor comes from a solid state control board which could be the problem.

if it is shutting off abruptly the limit is either wired wrong or set wrong. If the fan comes on and blows the flame out there is a hole in your heat exchanger which can result in fire or carbon monoxide poisoning. Have an experienced tech take a look at it to be safe.

A sampling of various failure codes on a furnace:

Read one LED flash that stays on continuously to mean your furnace has no signal coming from the thermostat and will not operate. Turn the power off and check the thermostat for improper settings or connections.

Interpret one LED flash that blinks on and off to mean your furnace has locked out because it could not ignite after three tries, and must be reset. Interrupt power to your furnace for 20 seconds or lower the thermostat so your furnace does not try to heat, then reset the thermostat to the previous setting. After one hour of lockout, your furnace will automatically reset itself and try to operate as usual.

Decipher two LED flashes to mean the draft blower is not working, or your furnace has a short in the pressure switch circuit. Turn off the furnace power and repair a short or replace the pressure switch.


Read three LED flashes to mean your furnace has an open pressure switch circuit or it has an induced draft blower operating. Check the pressure switch hose of your furnace for blocks or an improper connection. Also, look for blockages in the flue, and tighten any loose wiring.

Translate four LED flashes to mean your furnace has a primary limit circuit open, possibly from loose wiring or blocked filters. Check and clean filters, tighten wiring and check the flue for blockages.

Interpret five LED flashes to mean your furnace senses a flame without a call for heat. This could be from a gas valve closing slowly or a burner flame lingering.



Read seven LED flashes as a warning of a low flame sense microamp signal. This could happen with a coated flame sensor or a lazy flame from poor gas pressure. Turn off the power and adjust the gas pressure according to the information on the rating plate.



See eight LED flashes as meaning an igniter circuit problem due to a bad igniter or an igniter connected improperly. Replace the bad igniter or check the ground wiring, making necessary corrections.



Decipher nine LED flashes to mean the high-stage pressure switch circuit will not close during a high-stage-induced draft blower operation. Your furnace may have a pinched or blocked pressure switch hose, a blocked flue or loose wiring.

Read continuous flashing on the LED to mean your furnace has a reversed polarity of 115 volts. Turn off the power and correct the wiring polarity after reviewing the wiring diagram.


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Sounds like limit switch issue. Furnace heats up, high temp limit switch opens, fan will stay on. GMP model is older and do not have the codes.
May be over fired, have airflow problem, to cause the limit to open.
Next time before shutting off power, try to find the limit, it has two wires that connect to a 1.5 x 2 inch card mount to the furnace fire wall. tap on it and see if the blower stops. If so replace the limit.

if this is an error code and you mean that the light blinks 4 times then it is the limit circuit. This could mean either the high limit or a roll out switch is open. the limit switch is right in the center of the furnace above the burner and roll out switches are probably somewhere around the opening of the burner. Follow the wires from the limit to find a roll out switch cause they are in line with each other and the rool out switch could have a button to reset it. However if the roll out is not tripped then you could need to change the limit. Only way to know is to check for continuity.

Usually you can find the control board on the lower part of the furnace. Turn the power off and remove the
doors. This board is usually located directly in front of the blower motor.

On the control board locate the terminals marked heat/cool/park and Park Lets say the Heat Terminal
has a red wire attached to it and you want a higher
speed.

Red is uasually low speed, remover the red wire from
heat terminal and exchange it with a wire attached to
a terminal lab eled park. Black is usually high spped

Rewire to schematic specs and check po;larity of transformer. Rus

Sounds like the fan switch on the furnace is set to low. Turn power off to furnace, take door off of furnace look for a fan switch, it may be a fan - limit together. The limit settings should be approximately 160° to 200°, and the fan settings should be about 100° to 140° set it to 120° it it's already set there then you probably need to replace it.

Switch the leads and also make sure that you have a good ground.

The blink codes are differant on every furnace. Read your code on the schematic found on the inside of the door. You most likey have a dirty flame sensor. Under the burners you should find a "single" wire going to a connector. This will be to the far left or right. Just opposite of a "two" white wires going to the hot surface igniter. Remove the 1/4 inch screw closet to the single wire under the burner. carefully pull out the flame sensor. Clean it with a small piece of sandpaper. Re install it. This should fix your furnace. KEEP IN MIND Goodman GMP models are noted for defective heatexchangers. Pull out the blower assembly and turn it over. If small rings about the size of a dime falls out.... this furnace is unsafe and should replaced!