HVAC Questions? Ask an HVAC Expert for Answers ASAP
When is the last time the filter was changed?
Check to see if the filter is dirty.
Filter should be changed every 3 months.
would a dirty filter prevent the 4 burners from lighting
Yes. A dirty filter will cause the Main Limit switch to open and not allow the burners to light.
The Main limit switch will open because a dirty filter causes the furnace to overheat.
changing filter now
The main limit switch is usually a rectangular or square looking device that has two wires attached to it and is usually located inside the furnace cabinet on the back panel wall behind the gas valve. Locate it and let me know when you find it.
hammock style filter.. on one side very dirty
That is probably the problem.
changed filter- turned on heater- air is still not hot- burners are still not lit. i have located the main limit switch. any other suggestions
Do the main limit switch have a number such as this written on it, L180 - 40F ex...?
it has this on the front face of it FALTS57E-13T-110-1160 and on the bottom side it has this number 13B8501
sorry correction it is FALTS57E-13T-110-160
I dont beleive that is the Main Limit switch.
Give me some more description of it?
small black box behind gas valve on wall of furnace. it looks like it has also something to do with fan controll. It has fan off and temperature settings from 80 to 110 degrees and a small dial which is on 110 degrees
Yes that is the fan limit switch. I will opt out so another expert can assist you with this because I don't know how to bypass the fan limit switch.