Small motor noise behind steering wheel dash

The HVAC system has three servo motors in it. They control fresh vs. recirculate air, and distribution of air to the various vents. One of those motors is sticking.

Just turn the radio a little louder and don't worry about the sound - unless you really want to spend four digits to have your dealer mechanic take apart the dashboard for access to the HVAC system.

 

The servo isn't necessarily sticking. Each one has a position sensor built in, sending a signal back to the ECU so the motor can be driven to the selected position. If the Gen 2 servos are like Gen 1 (and I think they are), that's just a potentiometer that, with age, can start sending a noisy position signal back to the ECU, which the ECU then constantly drives the motor back and forth trying to correct for. This is no different from the Gen 1 noisy steering torque sensor, leading the steering ECU to shake the wheel back and forth.

Gen 3 moved to non-contact, magnetic position sensors in the servos, just the same way Gen 2 ditched the potentiometer torque sensor in the steering.

Sometimes the procedures shown in the repair manual are unnecessarily intimidating, like the Gen 1 manual saying to remove the valve cover just to get to the fuel injectors. These servos are like that. The manual may say to remove the dash for access, but that's just crazy talk. The air mix and outlet servos are both right there on the left side of the HVAC box, you just do a headstand in front of the driver's seat and take out three phillips screws.

The air inlet servo is the one that might be harder to get to, on the other side of the HVAC box between it and the blower, behind the glove compartment. But that doesn't sound like where this poster's sound is coming from.

It's a very quick DIY project to take the servo out, open it, clean the potentiometer contacts and traces, snap it back together and put it back in. Then you don't have the noise any more, and it isn't prematurely wearing itself out wagging back and forth. But I already covered all that in the post I linked to in #9 and mentioned again in #20.

-Chap