see this causes and fix it. God bless you
f there is no heat, check the electrical service panel
for a burned fuse or tripped breaker. Relight the pilot light (see below).
If there is not enough heat, adjust the burner air shutter (see below); and clean the burner ports (see below).
If the pilot light does not light or does not stay lit, clean the
pilot orifice carefully with a toothpick, test the thermocouple and
replace it if it is faulty (see below).
If the flame flickers, adjust the pilot (see below).
If there is an exploding sound when the burner ignites, adjust the
pilot to a higher setting and clean the pilot orifice and the burner
If the burner takes more than a few seconds to ignite, clean the pilot orifice and adjust the pilot light.
If the burner flame is uneven, clean the burner ports. If the burner
flame is very yellow, clean the burner; open vents in the furnace room
to provide more air; adjust the burner air shutter.
If the furnace makes a rumbling noise when the burners are off, clean the burner and adjust the burner air shutter.
If the air is too dry, wash or replace the evaporator pad if you have a humidifier; test the humidistat
; and adjust the water-level float to raise the water level.
If some rooms are too cool and others too warm, the distribution system may require balancing. Refer to the Forced-Air Distribution Fix-It Guide