I have a whirlpool gas furnace. I just changed the limit/control switch and my furnace is almost working perfectly except for one problem. The pilot light will go out frequently. It has no set pattern for going out it will be working fine and all of a sudden go out. Could it be just the thermocouple or could it be something else? Thank You.

Low pilot flame (orifice could need cleaning)

Thermocouple not putting out enough milivoltage (replace thermocouple)

Do you have trap door going up into your attic by any chance? Maybe a pull down stair case?

((Could be downdraft if it occurs during stormy weather, high winds))

It could very well be a problem but so can a hole in your heat exchanger snuffing the pilot out from time to time. Like always try the suggestions then if that fails call a pro.

Has it been that way for very long? If not, what might have changed?

Do you have trap door going up into your attic by any chance? Maybe a pull down stair case? Yes I do have a trap door in the hallway right next to the furnace, but this is the first year I have really had trouble with the pilot.

Has it been that way for very long? If not, what might have changed?
I actually removed the thermocouple about two days ago when I was working on the unit and reinserted it. The thermocouple is a universal type and it had slid down slightly causing the furnace to be difficult to light. The pilot stayed lit all night last night and the unit worked fine.

If it keeps going out it won't hurt to check the weather strip on the pull down stairs. Mine got pinched and when I opened the door I could see where air has been blowing by with surprising force.