Some 2015-2018 F-150 vehicles equipped with a 3.3L/3.5L Duratec, 3.5L EcoBoost and 5.0L engine and equipped with a block heater 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 -20Ã…?C (4Ã…?F). This condition may be due to deposits from the engine coolant becoming trapped in the heater core. Follow the Service Procedure steps to correct the condition.
