My Goodman gas furnace will run, but will not ignite. I do see a red light blinking three times through the peep hole.

Question edited for typos.

Gas furnaces has safety features to prevent explosions. If anything is thought to be faulty, nothing works. All gas appliances must be repaired by a registered gas technician. The two pressure switches are $76 and $29 if you want to risk it.

https://www.goodmanparts.net/category/goodman-gmv950905dxa-gas-furnace-oem-repair-parts

There is videos and help here. Check the hose on the pressure switch.

https://www.google.com/search?q=Goodman+GMV950905DXA++low+fire+pressure+switch+stuck+open

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very vague on information and question --check and test thermostat for correct operation and operating ---check gas is on --- check and test thermocouple --and other sensors [ clean or replace if failed ] check and test fan and relays

Clean your flame sensor first before you change that gas valve

There could be other problems but check and see if your igniter is not burnt out. Ours did that and tried to ignite for two days and then I found I had to change the igniter.

Power is there, or no lights would blink. Steady blinking or flashing three times, stop, three times Etc

The goodman furnace will try and light three time before it faults out for safety reasons. Adjust the flame sensor so that it is closer to the flame or actually in the pilot flame. If the flame sensor is inside the pilot flame and still does not stay lit, your flame sensor is probably defective and should be replaced. You can get one at Ferguson's counter sales.

you will neede to defrosted the flue clear any bushes or trees from flue if there ther eshould be a window on the front where you can see the lights hope this helps

you can jump the pressue switch out but some heaters you can not fool the heater it to thinking its working

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).
Your furnace has a diagnostic chart on the reverse of the lower panel incorporated in the wiring diagram. One blink tells you that it is a failure but wont tell you where to start looking.

There is a chart with the wiring diagram and othere charts that will tell you what the 6 blinks are for. That should tell you what is wrong and what part you need. Sounds to me like the board has an issue or the gas valve is locked out.