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Herb 1/7/2013
1999 Mercury Sable LS 6 Cyl 3.0L - Engine
Heating is very poor.
Heater core flushed. Was clean. New heater hoses,water pump, thermostat. Air in car only gets luke warm. Temperature of hoses at heater core range between 175-185. Just bought car. Wonder if heater controls are malfunctioning.
1 Answer
  • CVO
    CVO 1/7/2013
    The blend door actuator is a servo responsible for controlling the mix of warm air from the heater core and cool air from the A/C and outside. If it malfunctions, your climate control system may not respond properly when you change the temperature on the climate control system.

    Both the manual and the automatic systems use this servo to control the blend door. If your ATC system fails to automatically change temp, this is also an indicator that the servo has failed.

    See this Blend Door Actuator

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