What does an AC actuator do?


What does an AC actuator do?

The AC actuator moves air distribution doors to two or more positions to direct air flow for heating and A/C vents. The AC actuator is located underneath the dashboard attached to air distribution doors in the hvac box.

Doors can control warm air/cold air blending, recirculated/fresh air control, or dual zone splitting. The motors can move the doors into many different positions, or just two.

There are three methods used in the automotive industry to operate the HVAC doors or flaps for distributing cars in cabin air. These methods are: Cable controlled, vacuum motor controlled, electric motor controlled or any combination of these methods.

On two-position doors, the control module activates the motor to move the door from one position to the other, depending on what the driver selects. For instance, if the driver has the function selector set to outside air, the door will stay in the outside air position until the driver moves the function selector to recirculation air position. Once there, the door will stay in that position until the driver moves the function selector again.


What are the types of AC door actuators?

The cable type system, the driver controls the system manually. The cables move the flaps as the levers on the head control set are moved.

Early vacuum control systems used a vacuum control switch on the dash that, when operated by the driver, would direct engine vacuum to the corresponding actuator. Later vacuum control systems use electric switches, which send signals to a control module or controller, which in turn sends vacuum to the appropriate actuator.

Electric Actuator motors:

Electric Actuator motors used in modern hvac systems can be one of four designs, the electrical functions and circuits are different in each vehicle, Depending on vehicle manufacturer, system design, year and model:

The Electric actuator motor is a fixed speed DC motor, which runs in forward or reverse direction to move the hvac plenum doors  in your car between fresh air and re-circulation positions, hot and cold air positions and from vents, floor or defrost setting positions. The electric actuator motor consists of stators, slip rings, coils and a rotor, which contains permanent magnets. The actuator motor (servo motor) can be stopped at specific points in its armature with an accuracy of approximately 0.1 % providing a great control at keeping a constant in cabin air temperature under all driving conditions.

TRI-STATE hvac actuators

A tri state actuator is a five wire design. Three of the five wires are used for the feedback circuit. The other wires are for ignition voltage and hvac control head requests. These smart actuators move according to voltage received from the head control set commands. A certain voltage will move the actuator one way a different voltage will move it in the opposite direction and a different voltage value will be commanded for the motor to stop rotating.

BI-DIRECTIONAL hvac actuators

Bi-directional actuators use three wires for circuit feedback. The other two wires are the positive and negative circuits that drive the motor. These circuits are controlled by the HVAC control head set and move the motor direction based on the selection made at the control head. They are sometimes referred to as “dumb actuator” circuits.

THREE WIRE hvac actuators

The three-wire actuators have a power, ground, and an input wire from the hvac control head. These actuators use a pre-programmed logic chip containing all the information to drive the motor in the requested direction. When a position change is requested by the vehicle operator, a circuit in the control head sends voltage to the actuator motor. As the motor moves, a potentiometer in the actuator compares the motor voltage to the output voltage from the control head. When both voltage readings are the same, the actuator motor stops. There is no feedback to the control head with this design.

TWO WIRE hvac actuators

Two wire actuators create electrical pulses when the commutator rotates across the brushes of the motor. The HVAC control head, which has pre-programmed logic and actuator end point references, counts the electrical pulses as the motor moves the door through its sweep from one end to the other end.


How much does it cost to replace AC actuator?

The price to replace a damaged air conditioning actuator motor will be different depending on the make, model and year of the car and also if the new actuator will be an OEM actuator or an aftermarket actuator. The location of the actuator, depending on the hvac box design is the main factor taken into consideration when calculating the price of the service. Some actuators could be really hard to reach; and in many cases the entire dashboard must be removed to gain access to the ac actuator. A price range could be very hard to set because of the many combinations on today’s hvac box designs. The price range could be from $ 125.00 to $720.00.


How much does actuator cost?

The price of the AC Actuator will depend on:

The make model and year of the car.

Aftermarket AC Actuator replacement or OEM AC Actuator replacement.

Type and design of the actuator: Electric actuator, vacuum controlled actuator or cable control.


What are the symptoms of a bad actuator?

Air coming out from the wrong vents, clicking noises coming from behind the dashboard or not being able to control the temperature or re-circulated or fresh air mode in your car is a sign of a bad air door actuator motor. Exhaust fumes inside the cabin.


What are the symptoms of a bad temperature blend door actuator?

Air conditioning temperature can’t be regulated. The driver, passenger or both, depending on the design won’t be able to control the temperature on their climate zone. Decreased air conditioning performance due to improperly mixed of hot and cold air inside the hvac box.


What are the symptoms of a bad mode door actuator?

The symptoms of a bad mode door actuator are clicking noise coming from behind the dashboard. The driver, passenger or both won’t be able to regulate the position from where the flow of air will come out of the vents. Weak or not at all flow of air coming out from the vents.


What are the symptoms of a bad recirculation air door actuator?

The symptoms of a bad recirculation air door actuator are clicking noise coming from behind the dashboard. Exhaust fumes inside the cabin. Poor ac performance due to the outside hot air leaking into the hvac box and then the cabin compartment.


How to test the blend door actuator motor?

There are some simple tests that could be done in order to determine if the vehicle is having issues with the blend door actuator:

If you can’t set the temperature from the head control set selector, there is a problem with the blend door actuator, the blend door, the head control set or the circuit connecting them.

For every movement of the knob on the climate control set corresponds a movement on the blend door. If there is no movement, there is a problem with the blend door actuator, the blend door, the climate control set or the circuit connecting them.

As the blend door open or closes to the heat or cold position it opposes the flow of air coming from the blower motor and makes a change in the intensity of the air noise. If you can’t hear this change in air noise intensity there is a problem with the blend door actuator, the blend door, the climate control set or the circuit connecting them.


How to test the mode door actuator motor?

There are some simple tests that could be done in order to determine if the vehicle is having issues with the mode door actuator:

If you can’t set the flow of air to come out from the right vents position using the head control set button, there is a problem with the mode door actuator, the mode door, the head control set or the circuit connecting them.

For every movement of the knob on the climate control set corresponds a movement on the mode door. If there is no movement, there is a problem with the mode door actuator, the mode door, the climate control set or the circuit connecting them.

As the mode door open or closes to the floor, panel and top it opposes the flow of air coming from the blower motor and makes a change in the intensity of the noise. If you can’t hear this change in air noise intensity there is a problem with the mode door actuator, the mode door, the climate control set or the circuit connecting them.


How to test the recirculation air door actuator motor?

There are some simple tests that could be done in order to determine if the vehicle is having issues with the recirculation air door actuator:

Exhaust fumes inside the cabin. Poor ac performance due to the outside hot air leaking into the hvac box and then the cabin compartment.

For every movement of the knob on the climate control set corresponds a movement on the mode door. If there is no movement, there is a problem with the recirculation air door actuator, the recirculation air door, the climate control set or the circuit connecting them.

As the recirculation air door open or closes to the re-circulated or fresh air position the flow of air coming from the blower motor makes a change in the intensity of the noise. If you can’t hear this change in air noise intensity there is a problem with the recirculation air door actuator, the recirculation air door, the climate control set or the circuit connecting them.

Call Auto A/C Repair LLC. If you are experiencing any issue with your car’s air conditioning. We have the fastest road service response time in Miami. Call Auto A/C Repair the a/c repair always near you!!!

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