funace issues

[semperfi]

I have a Fraser Johnson Model FG9B06012DH11D. What started as an occasional issue now occurs almost daily. The furnace will fail to start when the temprature drops and the thermostat signals it to start. It will always start several hours later after the home has cooled down way below the setting. You can hear the furnace click and make a noise as if it is starting but the burner doesn't light even if you you turn the thermostat off and turn it back on and lower the setting. The repaiman says it appears to be in lockout and he has tried several things to no avail. Most of the time the furnace is working when he gets here and I know it's hard to diagonose an issue when none is present. When we got up this am it was 63. Around 9am the furnace started up without touching the thermostat. Now it's warm and no need for the repairmans visit. Please help!

[how]

Check if your unit has a blinking diagnostic led light. Look through the grill of the furnace door or through an inspection port. The furnace will also have a legend on the back of the furnace door that will explain those codes.
Does your unit have a spark igniter or a glow coil? Do you have an inducer motor that starts up as soon as the thermostat calls for heat?
Do you have a pilot light that ignites before the main burners?

[gibby]

i would try to bypass the stat first to verify that you don't have a bad stat before diving in the furnace

[how]

Bad stat does not cause a lock out. (if the repairmans diagnosis was correct)
Verifying a led blinking light will give him the chance of a fault diagnosis the next time the furnace locks out without him even needing to dive into the furnace.
A stat bypass or a (W & R) pigtail is the right action if the board shows no sign of a fault code.