A long time ago, when cars were much more simple, the A/C system’s blend door was controlled by a physical connection between the blend door and the switch. Not anymore. Now, most cars and trucks use actuators to control the climate control system. When the blend door actuator fails, you’ll usually know pretty darn quick that it happened. Below, we’ll cover the most common symptoms of a blend door actuator, with the hopes that you can take the information and use it to get back on the road again as quick as possible.
What a Blend Door Actuator Does
A blend door actuator receives input from the climate control system and changes the blend of hot/cold air entering the vehicles cabin. It can take input directly from the climate control switches, or if your vehicle has a sophisticated system it can be adjusted by the computer to maintain a constant temperature.
Symptoms a Blend Door Actuator is Bad
Here are some of the most common symptoms that a blend door actuator has gone bad:
1. Clicking Sound
If you hear a repeated light clicking sound coming from under the dash, it can be a bad blend door actuator. Often, adjusting the temperature settings ever so slightly can stop the noise temporarily. When you change the temp setting in your car or truck normally, you will typically hear the this noise for a few seconds. When you hear it over and over again, that’s the tell tale sign that the actuator is going bad.
2. Wrong Temperature
If your car or truck that has an A/C that is blowing too hot or not heating up, that can be a strong indication that a blend door actuator is bad. But, the wrong temp can indicate other issues as well.
If it is the blend door actuator (or a hung up blend door) that is causing the issue, the vehicle will either be stuck at a certain temperature, or it’ll only be able to go so high or so low before any further input fails to register.
3. Two Different Temperatures
In vehicles with dual climate control, if the climate control is responding to one side of the vehicle, but stuck on the other half, that indicates a bad blend door actuator.
Common Misdiagnosed Items
Here are some common problems that are really occurring when people assume that they have a bad blend door actuator:
Air Conditioner System
Often, people will assume that the blend door actuator has gone bad when the heat or A/C stops working properly. If the vehicle in question still has heat that is blowing hot, but not reaching the desired cold from the A/C system (or vice versa) it can indicate issues with the heating and cooling directly.
In the case of the Air Conditioner, if the coolant is low, you can usually tell. Turn the air conditioner on full blast with the engine cold. If the air gets hotter as the engine warms up, you know that it is a blend door issue. If it blows warm from the time you turn the engine on, that would indicate that the A/C system is malfunctioning.
The logic behind this is that it takes the heater a minute or two to warm up. If you have it set all the way to cold, there should be no change in temp as the engine warms. If it does change, the blend door is still letting heat through. This would narrow it down to a bad actuator or a stuck blend door.
Bad Heater Core
If you are getting cold air from the A/C, but the heater just won’t blow hot, you’d want to make sure that the heater system has not gone bad. A bad heater core will not let heat enter the cabin, even with the actuator and blend door functioning correctly.
Also, make sure that your vehicle is reaching the proper operating temperature. If the thermostat is stuck open, it’ll keep it from getting hot enough to get the piping heat that you have come to expect.
Stuck/Frozen Blend Door
While it may be very likely that the actuator has gone bad, don’t overlook the blend door itself. It’s not unheard of for them to freeze into place on long trips where they don’t move at all. If you happen to be reading this article after having travelled a long distance, know that it’s entirely possible that the blend door will be unfrozen and functioning perfectly fine after a few hours of the A/C being turned off.
Even if it’s not frozen in place, it is possible that something is blocking or has made it to where the blend door won’t move freely on its own.
Conclusion: Bad Blend Door Actuator Symptoms
While it can be tough to get to a blend door actuator, the number one symptom is a clicking sound along with the climate control not responding to your input. Good luck fixing your vehicle!