if it's a 90 % furnace you may have a flue or intake air problem or a bad pressure switch make sure you are venting the flue gases and the fresh air intake is clear
A competent HVAC Contractor in your area
How do I light pilot light on furnace
I believe it is called the "pilot light"
Pilot light for what? There should be no pilot light on a heat pump. Is this another silly homework/exam question?
How do you relight a natural gas pilot light?
At pilot light, pilot light flows around thermocouple.
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How do you reset service light in 2003honda pilot
The pilot is just 'the pilot'
At pilot light, where pilot light flame goes directly onto thermo coupler.
It could be different for every house.A side note: I'm taking that you mean where is the pilot light located in side your furnace? Depending on the of your furnace it's very possible your furnace does not have a pilot light, in fact it may have an ignition system with a flame management sensor. Try this; turn off the system with the main electrical cutoff switch, wait for about 2 minuets, turn on the switch raise the temperature of the thermostat high enough for the furnace to come on, this should work if it does not try one more time. If that fails call a HVAC & R technician.
If the pilot light is on, the heater should come on by itself. If the pilot light is off then it has to be lit. If it will not stay on, the thermocouple is bad.