Goodman GMP075-3 ignition problem

Check the blower motor .Maybe that's what giving a humming noise .Could be just a bad capicator

I believe this code is ignition failure.
Turn power off and after 20 seconds turn power on with thermostat calling for heat. Vent blower should come on first. After a bit igniter should lite up. You should hear click noise of gas valve open up. If igniter does lite and you hear click noise, flame should come on for a few seconds minimum. If igniter doesn't lite and you hear click noise from gas valve, igniter is bad. If flame lites and then goes out, flame sensor probably needs cleaned. Both igniter and flame sensor are in metal plate under burners. Igniter has 2 wire going to it and flame sensor has one wire. If you think it is flame sensor you can remove with taking it out with 1 1/4" hex screw. Flame sensor will have white film on it if it needs cleaned, clean with steel wool or a dollar bill. If it isn't weither of these it is gas valve or circuit board.

It sounds like you got a tough one there.When you say the blower starts up and then the igniter comes on are you refering to induced draft motor or main blower. The proper sequence is for the thermostat to call for heat at which point the induced draft motor should come on and run for 30-45 seconds,then the igniter should heat up for a few seconds then gas valve should open and main burner should light. After limit switch reaches set point for fan on ,blower should come on till after heat has reached thermostat setting then burner should go out, and blower run until fan off setting is reached on limit switch. If your furnace is not following this sequence and then not always doing the same thing in the same order,I would recommend that you change out board again. I have had several problems similar to this with Goodman units and all but one time installing new board solved it. That time I did everything I knew to do and talked to factory service techs repeatedly and finally installed new furnace. As far as your question about insulation,. As long as it is fire proof I can't see where it would hurt anything. Sorry I'm not more help. Good luck and thanks.

Problem: Your furnace will not ignite the gas to produce heat for your home. When a furnace has a bad igniter what I see most of the time is the following sequence of operation:


1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back off and on again. Then the sequence starts all over again with no ignition of the gas.
Solution: You probably need to purchase and install a new igniter. I would suggest that you inspect your igniter closely for cracks. Make sure you do not touch the igniter with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, roll-out switch problem. The furnace's control board might not be supplying the voltage to the ignitor. If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then you need to clean your flame sensor with light sand paper or steel wool. You might need a new flame sensor, but most of the time they can be cleaned an will work well after cleaning.

NATE, NCCER, PHCC,HVAC Certified Instructor

4 flashes is an overheat situation most likely caused by the blower not blowing. The blower relay controls the blower function. It is part of the circuit board. I suspect a new board will take care of the problem if you don't find a lose wire or something simple.

I would first look at any wire connections both at the furnace and the thermostat. Then I would replace the thermostat. Check the units control board when it does not start for an error code. There should be a small viewing port to look into the furnace cabinet to see the control board.

On a call for heat, the 24 volt thermostat sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the igniter. The igniter will glow and you will be able to see it if viewed thru the small inspection port. Once the igniter gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two.

What could go wrong? The unit will not run if there is no signal from the thermostat (bad thermostat or broken wire), the control module does not sense a signal from the thermostat (bad control), the inducer does not energize (bad motor), the pressure switch does not close (blocked vent piping, bad switch, plugged condensate hose), the igniter does not energize (bad control, bad igniter), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not light (dirty pilot), the burner does not light (bad burner, plugged orifice, not enough combustion air), the flame does not spread to each burner (bad flame spreader, dirty flame spreader, more bad burners), the flame safety sensor does not detect flame (dirty or bad flame spreader, bad flame sensor, broken wire, bad control), or the room air blower does not energize (bad fan motor, bad control).

Here is the ignition sequence for a spark ignited furnace. This will help you understand what is happening/not happening.

Thermostat calls for heat.

draft inducer motor (DIM) starts drawing draft through heat exchanger.

Pressure switch detects proper operation of DIM, and sends signal to board to begin ignition.
(it detects negative pressure)

Ignitor starts ignition attempt and gas valve sends gas to burners.

Upon ignition, flame sensor detects flame and sends signal to board stopping ignition sequence and continuing gas flow for heat mode operation until thermostat is satisfied.

During this sequence the blower motor is brought on, and by using a series of temperature limit switches, the system assures that the unit is operating properly.
(If the blower is not operating, or the airflow is inadequate, the heat exchanger will overheat and trip one or more temp limit switches.)

There is also a "rollout" switch that detects improper flame pattern "rolling out" into the controls compartment.

Now, to apply that to your situation.

If you have no spark, than the failure is happening before the gas is supposed to be flowing.

That usually means a failure at the D.I.M. Typical causes for that are a clogged flue pipe/vent, damaged/deteriorated fan blades, bad fan, or bad pressure switch.

If one of the temp limit switches or rollout switches have tripped, it will simply shut off the system.
(Some units will turn on the blower motor and shut down everything else.)

You can try resetting the unit by disconnecting power for 1 minute, and attempting a restart.

First look for any flashing LED lights. If you see any locate the wiring schematic (usually on the inside of the front panel) and look for the flash codes.

If the reset does not solve the problem, let me know what flash code you are getting, and/or let me know exactly what you see the furnace doing, in detail, after the restart.

jump out thermostat or try jumping out the pressure switch

can you write down where the low voltage t stat wire go and disconnect the white wire at the unit to eliminate a short between the white wire and the red wire usually the colors are as follows red is 24volt , green is fan , white is heat, yellow is cooling I want to narrow down the red is not shorting to the white briefly let me know if this is possible if not we can try other checks

your polarity wires need to be reversed the main wires coming into the unit are either black going to black white going to white changed the wires around to black going to white and white going to black that should solve your problem