Odd Sound coming from A/C

I turn my ac compressor off all the time. That doesn't stop the fan. Turning the fan off stops the fan. Hopefully the garage figures it out for you.

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I wouldn't so much describe the servo sound as clicking. It sounds pretty much exactly like a small electric motor moving a geared linkage slightly back and forth (which can sound, well, a little bit like a mouse quietly scrabbling around in there, but not really). In that thread I just linked, I included a video with audio of the sound (and with the camera pointed at the servo linkage, so you can see what you're hearing ... so many "videos" of it have the camera pointed at the floor, or the dash, or the brake pedal....).

In my Gen 1, where I made the video, both of the servos on the driver side (one for the temperature and one for which outlets the air goes to) are really easy to get to, once you slide upside down on the seat and get your head in there. The third one (for air inlet, fresh/recirculate) is on the other side and much harder to reach (dash cover off, probably).

I think Gen 2 kept the same basic layout pretty much, but they also bolted in some new ECU down close to the driver's side of the heater, where it's in the way of reaching one of the servo mounting screws. Somebody very recently posted a thread here about buying a very low-profile offset screwdriver on amazon and successfully undoing the mounting screw with it. So recently I can't find it in google yet, and I've just now tried the PriusChat searching some and given up finding it that way. Too bad, 'cause it was a good post, and will be helpful if you ever happen to find it.

Gen 3, I think, made them all hard to get to.

-Chap

 

When My MFD screen displays the words “Air conditioning OFF “ so is the blower fan. This is different than turning off the A/C via the button on the display screen. The button just turns off the A/C compressor while allowing the blower fan to continue to operate in VENT or HEAT mode.


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Which is what I was attempting to say. Thanks for clarifying. Just because the ac button is turned off doesn't mean that the system isn't utilizing the blower causing the sound to continue. I hope to know what the OP determines the problem to be... Best wishes!

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That would certainty eliminate your blower motor or debris trapped therein. I sure hope it's something just as simple!

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The heater is a big plastic ductwork construction occupying most of the space behind the middle of the dash. The two servos (for the air temperature mix, and the air outlet selection) are in plain view on the side of that, facing into the driver's footwell. They look like the pictures you've seen of them, and have white plastic cam segments/linkage rods that they move to flop the duct doors around.

They're pretty hard to miss, really, once you're down there looking. Especially if they are wiggling their white linkages back and forth making mouse-scrabbling noises. Or, if they're not, you can reach your hand up and work the heater controls and watch for the things that move. (The third servo is over on the passenger side of the heater, much harder to see, but you might be able to get a glimpse if you take out the glove box).

You probably won't find that they need any grease, they should be plenty well lubricated. You'll just want an electrical contact cleaner to clean up the resistive contact paths that are how they send their position back to the controller.

What happens is those get electrically dirty, and they send back a position signal that keeps jumping around. The controller wants the door to stay in one place, so every time the position signal electrically jumps this way, the controller commands the servo to move that way, and then when the electrical signal jumps that way, the controller tells it to move this way, and on and on.

-Chap

 

The post I was thinking of is this one.

-Chap

 

Yes, the one for the fresh vs. recirculated air intake is on that side. My understanding is that it's quite a bit less convenient to gain access to.

You might, by removing the glove box(es), be able at least to see the linkage or the flap moving, and confirm that it is the problem.

-Chap