Some 2015-2019 F-150 vehicles equipped with a 3.3L, 3.5L Duratec, 3.5L EcoBoost and 5.0L engine and equipped with a block heater built on or before 1-Jan-2019 may exhibit a lack of heat concern from the heating ventilation and air conditioning (HVAC) system when operating the vehicle consistently in temperatures that are below -20Å’C (4Å’F). This condition may be due to deposits from the engine coolant becoming trapped in the heater core. To correct the condition, flush the cooling system and replace the heater core. Follow the Service Procedure steps to correct the condition.
