I have a carrier central air & heat. When set to auto - fan for heater, the fan attempts to turn on and then stops. When I set the fan to on it turns on. What could be the problem? The thermostat is set to 70 and it is 60 deg in the house. Thermostat shows that the heat is on even though it is off. Thanks for any help

Wow another no exact model number furnace. They must of made many of them.