Cabin air filters first appeared on the Ford Contour back in 1995, and they were added to the Ford Taurus in 1996. These were 25 Micron filters, and like all cabin air filters, they do a wonderful job of keeping dust and pollen out of the engine compartment when the A/C is being run on βNormalβ rather than βMAX/Recirc.β
The heater may stop working in Ford S-Max due to low coolant level or air in the cooling system, clogged heater core, bad thermostat, faulty blend door actuator, bad water pump, dirty cabin air filter, bad blower motor, or HVAC control unit malfunction. 1. Low coolant or air in the cooling system. Low coolant level or air in the cooling system