When This May Happen

• The furnace is still warming up

• The thermostat fan is set to ON

• The system is in defrost or safety mode

When It Is a Problem

• Cold air blows for a long time

• The house will not warm up

• The furnace turns on and off often

When to Call a Professional

• Cold air never turns warm

• The furnace shuts off quickly

• You smell gas or burning