Heat in Car

Bill

• 424 Answers
• Posted on Nov 09, 2009

SOURCE: 2005 Ford Focus ZX4 AC switch in dash does not

Sounds like there is a foreign object in the heater case. The only way to reapair it is to remove the object by possibly removing the heater case.

Testimonial: "Definately pointing in the right direction. Thanks..."

SOURCE: Blend door for front temp control is stuck in the

Control System Inputs
Climate Control Assembly
The climate control assembly has three control systems:

• The A/C heater function selector switch combines a vacuum selector valve for direct control of the vacuum control motors and electrical input to the instrument cluster module.
• The temperature selection is accomplished with a potentiometer connected to the electric blend door actuator that controls positioning of the temperature blend door. Movement of the control knob (18519) from COOL (blue) to WARM (red) causes a corresponding movement on the air temperature control door and determines the temperature that the system will maintain.
• The blower motor switch controls the blower motor speed through a series of resistors and a relay.

• The assembly is located on the passenger side of the plenum assembly behind the glove compartment (06010).
• Three resistance elements are mounted on the resistor board to provide four A/C blower motor speeds.
• Depending on the heater blower motor switch position, series resistance is added or bypassed in the A/C blower motor circuit to decrease or increase A/C blower motor speed.
• An overheating protective device (thermal limiter) will open the resistor coil circuit when the temperature reaches 121°C (250°F), interrupting the blower motor operation in all speeds except HI.
• The thermal limiter cannot be reset.

• Its function is to move the air temperature blend door on command from the control assembly.
• The A/C electric blend door actuator contains a reversible electric motor and a potentiometer. The potentiometer wiper is connected to the actuator output shaft and moves with the output shaft to indicate the position of the air temperature blend door.