My Goodman GMNT060-3 furnace will not ignite. I have replaced the pressure switch, control board and ignitor so far and no luck.

Verify if a 120 volts is being sent to the igniter after the pressure switch closes, if you are not receiving 120 to the igniter this could be a faulty control board. If you are receiving 120 then most likely the ignitor is faulty.

Check your conection off the board to the initor and make sure the pins in the plug are set tight with the connection on the board. If you wire nutted the wiring together for the new ignitor you installed check these connection also. Make sure all wire strands at the wire nuts are in the wire nut and not touching or arching on the furances cabinate.

This is probably a ignitor.

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 ignitor. I would suggest that you inspect your ignitor closely for cracks.Make sure you do not touch the ignitor with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, rollout switch problem. Please see "limits, rollout switches & furnace control boards" further down on this page. 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.
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Problem: Your furnace will not ignite the gas to produce heat for your home. When a furnace has a bad ignitor 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 ignitor. I would suggest that you inspect your ignitor closely for cracks. Make sure you do not touch the ignitor with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, rollout 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.

This could be the control board itself or even the pressure switch could be defective. There is no easy way to check if the board is bad, the pressure switch can be checked by pulling the small hose off and actually sucking and blowing into the tube while it is connected to the pressure switch. you should here a small clicking sound if it is working. You may try to clean the nipple that the hose attaches to on the idm housing with a small piece of wire. Also make sure your flue pipe is not restricted in any way, that could cause the same problem. Hope this helps and good luck!

The pressure switch requires a negative pressure (vacuum) to close the contacts. It is measuring the pressure in the inducer and indirectly ensure there is good combustion airflow throught the heat exchanger. Check for a small vacuum, in the neighborhood of 1" water column. Usually the vacuum required to close the switch is stamped on the vacuum switch. Check the vent pipe for obstructions and correct size and installation.
If the pressure aka vacuum switch does not close the furnace will not continue with ignition, for safety reasons.

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 ignitor. The ignitor will glow and you will be able to see it if viewed thru the small inspection port. Once the ignitor 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 ignitor does not energize (bad control, bad ignitor), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not lite (dirty pilot), the burner does not lite (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).

Most newer furnaces will have a diagnostic center or control built into the control module. You may be able to view it as it is running thru a small viewing port. Some models will require the removal of an access panel prior to finding it. On the reverse of the access panel, there will be a diagnostic chart that will aide you in understanding any error code recorded (usually a blinking light).

If your igniter comes on but no ignition, that eliminates the possibility of a bad or clogged pressure switch, high limit or flame rollout switch. Sounds to me like you have a control board, or a gas valve going bad. Could even be some loose, corroded, or faulty wiring. Before the igniter comes on the furnace does a self diagnostics to ensure everything is working, or the furnace will not make it to the igniter sequence. Inducer motor, pressure switch/s, limit controls are closed…then comes on the ignitier, gas valve opens, pilot runners and burners ignite, flame sensor detects the flame, blower comes on and all operations are working.

Hope this helps

Goodman gmp075-3 gas furnace and the flame cycles for 4 sec

OK, if the furnace is not lighting for even a few seconds, you have either a bad gas valve, bad wire, bad control module or no gas. The pressure switch is not the issue. Check all wires to the gas valve and look for 24 volts across them when the ignitor glows and you hear the click. Then test for 24 volts to ground. It could be a bad ground wire.