How to Replace a Blend Door Actuator?

Figure 1: Dorman 604-935 HVAC Blend Door Actuator.

Blend door actuators control the temperature and flow of air in the vehicle. If your vehicle only releases cold air, or you can't change the airflow, it may be due to a faulty actuator. Sometimes repairs require recalibration, and sometimes you need to replace broken parts.

1. Signs of a Faulty Blend Door Actuators

How do we know if our blend door actuators don’t work? They would generally show the following signs.

1.1 Noises

If you notice a humming or continuous screeching sound somewhere in the dash panel near the center area, there is a problem with the blend door actuator. This is most noticeable once you turn on the air conditioner, or change the temperature and heighten the setting.

In many cases, you will notice this noise if there is a complication or problem with the plastic gears inside the actuator. If any of the teeth are damaged or worn, the gears will start to slip and make a disturbing noise. After all, these gears are just plastic and they are subject to wear at higher frequencies.

1.2 Knocking Sound

Knocking rarely happens, but if you notice it, chances are you have a problem with your blend door actuator. If you start the vehicle, or just turn on the AC system and hear a knocking sound, this may indicate a complication with the blend door actuator.

1.3 Wrong Temperature

When you set the air conditioner to release cold or hot airflow, it would normally do it accordingly. If you set it for cold air but it still gives out hot air even a few minutes after the setting, it is the very indication that you need a new blend door actuator.

Figure 2: Left Temperature Actuator Location - Signal System Temperature Actuator.

1.4 Abnormal Airflow

If the motion of the blend door moves back and forth, the airflow may be held incorrectly or redirected incorrectly. This is a clear sign that there is a complication with the blend door actuator.

If the airflow from the vent is inconsistent, there may be a problem with the blend door actuator. This happens because the blend door moves back and forth, diverting the airflow and causing inconsistent airflow out of the vent.

2. Instructions on Replacing

After confirming that a blend door actuator is faulty, we can replace it according to the following steps.

2.1 Step 1 Remove the Dash Panel or the Glove Box

The replacement needs a specific kit, which you can order online or purchase from a nearby repair center.
First, using a small socket and ratchet to remove the bolt, you can remove the plastic cover under the dash panel of the car. With the cover off, you can see the wiring and various controls there.

Figure 3: Circled left blend door actuator.

2.2 Step 2 Remove the Actuator

Here you will need a small screwdriver to separate the wiring safety clip from the actuator. Gently remove the wiring connector and release the actuator. Check for broken wires or rust around.
Next you may find more screws that can be easily removed with a screwdriver. Remember to place all screws safely lest you lose them. Once all the screws are removed, you can pull out the actuator for further operation.

Also, manually turn the airflow door in both directions to make sure that it is not stuck. And ensure there are no obstructions blocking the airflow door. Remove dust and debris before installing a new actuator. Note that when purchasing an actuator, it should match the current actuator. Check the identicality of the wire harnesses as they should be properly connected to the terminals.

2.3 Step 3 Install a New Actuator

Now, it's time to install the new actuator. Install it in place of the old actuator. When tightening the screws, don't over-tighten them as they are installed in a plastic housing that can break. Once the screws are in place, apply a little pressure to the wiring harness connector to fit into the actuator. When you hear a click on this push function, the connector is properly installed.

When you're sure all the wires and bolts are securely installed, it's time to put the plastic cover back on. Once the plastic cover is in place, use the mounting screws to fasten it. You need to put everything back in place. Use climate control to check if the blend door actuator is blowing hot and cold air.

Figure 4: Respective position of each component of air conditioning system of a vehicle.

3. Conclusion

If the problem is not resolved after following the steps above, please make sure that you have done it correctly. You can also take your car to a professional repair shop for an in-depth inspection and confirmation.

Related Info