Heating tune up in Snellville, Georgia. Customer as wondering why fan for system was running at night. Found fan set to “on†on thermostat, switched it to “autoâ€. Performed heating tune up while I was here per customer request. Tested mechanical and electrical components and found no issues. Changed filter. System is heating at this time. System only has furnace, customer has no ac. Recommend installing condenser and evaporator coil so home has central air conditioning. System is heating at this time.