[luc12]

hello...i have a 4 year old(give or take) electric 25 kw nortron furnace....the fan drops to low when the t-stat tells it to shut off and it stays on forever...only way to shut it off is with main breaker...no switches were tripped or touched..everything worked fine all 4 years so it`s not a bad wiring job issue...the fan alone,no heat, decided to stay on a few weeks ago....there are three switches on furnace itself...summer switch is set to heating.....energy saver switch is set to cold weather..... fan control switch is set to automatic....there`s also a green light on the furnace which says t-stat on....t-stat controls are set to heat and auto....these switches have been like this all winter.....now fan won`t shut off..there is also an air conditioner hooked up to this unit....25KW, 240 Volt D Series Electric Furnace
Model 21D25....no model # written on furnace...not positive on model #....how do i trouble-shoot this problem so i can buy whatever part i need????which wires do i pull to test this and that?????please help....