I have an armstrong sx ultra 80 gas furnace the pilot is lit but the burners will only come on when I take the door off till they light and then I put the door back on once the temp reaches the level on the thermostat it will shut off it will not come back on when the temp drops until I go and do the process all over again

Where is the furnace located? something has happened to cause the furnace to not get enough air

It won`t hurt to leave the door off,as long as there nothing close by that is flameable, JUST until you can get more info as how to fix, I`ve seen people run them for years with no door, as long as the door that covers the blower compartment is closed

My furnace is located in the basement. Where is the blower compartment. Cause the door I have to take off is the one on top where the pilot and the burners are located

Can you post some pics of your furnace and furnace vent, along with the top furnace cover (which you have removed)?

The blower compartment is on the opposite end