When I turn thermostat on for heat,the gas will not ignite--I get 4 red flashes on my control board indicating (Thermal Detection Device Open).Does anyone know where the reset switches are?If I could find them I could possibly find out which device is faulty&staying open.The unit is an American Standard Freedom 80, made by the Trane company.The unit was installed in 1996. Can someone please help?


Model#AUD100C948H3

Serial#L373N7J2G