AcuraZine - Acura Enthusiast Community - AC/Dashboard making a knocking sound?

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AC/Dashboard making a knocking sound?

My 98 RL with 270k miles on it was making a weird noise coming from somewhere in the AC vents or maybe the dashboard/firewall. I drove about 25 minutes across town and when I got home I turned the car off and pulled my phone out to reply to a text. About 45 seconds after I took my key out of the ignition I started hearing a knocking noise from that area. I have a video on twitter that you can watch

with a decent sample of it. Again, car was off, no accessories were on except for the AC mode display on my dashboard, which I think is always on for some reason. I’ve never heard this noise before and want to figure out if it’s an issue. By the time the noise started all of the fans/motors would have stopped rotating (I would think). If anyone has any ideas what it could be it would be much appreciated if you could share them. Thanks!

btw, I had the AC on 68 degrees Fahrenheit and the air temp outside was around 80 I think. AC was somewhere between medium and full blast. Including all details I can think of in case they’re relevant. Thanks again.

Hey. I think it may by the Air Conditioner Servo Motor, probably the Air Mix Servo. Try manually selecting the Air Mode in the different positions (Such as Centre Vents, Bi Level, Floor Level, Defroster) and see if the air comes out correctly in each position.

Also try the temperature setting and slowly change the temperature and see if cold/hot air is coming out correctly to the temperature displayed on your climate control.

I am not sure about how to remove the Servo, but I am sure it is in the repair manual? I would try these first to see if you can locate which AC Servo Motor is the problem.

And I don't think it is normal for the AC Mode to be displayed when the car is off? This is why I am thinking it might have to do with the your AC Electrics/AC Servo Motor.

Let me know what you are able to find out.

Quote:

Originally Posted by rangeroverhse8 (Post 16286137)

Thanks for the help, I found that air is constantly coming out of the top vent to the left of the steering wheel and the top passenger side vent, no matter what mode it’s set to. The top center vent opens and shuts correctly according to what mode I have it set to, as do the floor vents. It’s currently 90 degrees outside which may affect what temperature I’m feeling coming from the vents, but it feels like it blows colder than it should until I turn the temp knob all the way up. There’s a very distinct difference between setting it to 89 degrees and setting it to 90, and anything between 60-80 feels colder than it should and then it starts to feel more accurate above 80, but again, it could be just relative to how it feels outside. I also couldn’t feel a huge difference when I turned it from the high 70s down to 60 again. I should be testing this with a thermometer but since I don’t have it, my guesstimates will have to do. I recently bought a service manual (I’m doing head gaskets Labor Day weekend) so I’ll refer to that to figure out where the servo is. As of right now it’s not a major issue, but the noise did freak me out because it’s new. I just wanted some ideas as to what it could be. Thanks again for your help, let me know what you think.