Good morning.

One of my many personal projects is a 1992 300TE and I'm trying to sort out this odd clicking sound that just began to occur. It sounds like it is coming directly behind the gauges on the dashboard. When driving, the clicking occurs at approximately 3 second intervals however when I stop it no longer clicks. Any idea what this could be? Thanks in advance for the help.

 

My ‘93 300CE also has begun making the clicking noise. Is it the time of the year?😊

 

Odometer gears in the cluster or speedo cable - either one on the verge of going.

 

Skipping odometer gears in instrument cluster likely.Notice if an odometer is not functioning when driving (mileage or trip). A simple trip odometer reset back to 000 may cure the issue.

 

If odometer isn't it.....and it does it at the first of a drive, at low speed... It could be the ABS doing a self diagnostic test. Sometimes it's just really noticeable. Will appear to come from dash cluster... If it does occur at lower speed... just push down on the brake pedal to see if it quits.

 

Do HVAC mode solenoids do this?

 

My ‘93 300CE will do it from time to time in the morning at low speed. Then it goes away for a few days. Not sure what the intervals are but my mechanic say the speedo gears/cable may be going…

 

good point, they can cause this noise, seems I had to have a "mixing" valve replaced years ago.

 

I had the same thing with the odometer. If it gets more frequent the faster you are going, it's that one. When I reset the partial odometer, the reset might get stuck (I guess some spring isn't working any more as it should) and I just need to press it a few times to unlock it.

 

Just don't reset it while the car is moving. That will kill the odometer after many many resets. You probably already know this.
If you only reset while the car is stationary the odometer will probably outlast the car.

 

Oh no, I normally reset the odometer after refueling when I'm still at the pump, I like to check what the consumption is. It's just some spring inside that is not pushing as before -and after 32 years you might expect it, after all- and it needs some help to go back.

 

As for me, I do not touch that reset any longer. First odometer lasted 170K miles and I used to reset it while driving and stationary, Second one is at 140K miles and it has not been touched by me in a long time. I keep track of the mileage by jotting it down on a note pad in the glove compartment on every fill-up. Not too keen on replacing the cluster/odometer again.

- Cheers!

 

So the issue has been resolved, I think.
I took it to the dealership for the periodical inspection and also asked them to check this temperature issue, and they changed the temperature sensor in the dash, behind the steering wheel. That apparently fixed the problem, as now I was getting warm
or cold air according to the temperature I set.
however, rarely I noticed I was still getting somewhat warm air when I was supposed to get cold, namely at 24 degrees Celsius. I didn’t know why, but after some time I also noticed that if the temperature outside is less than 18 degrees (was checking the outside temperature in the instrument cluster), then the 24c in the car would be warm air. If outside there were more than 18c, then the air inside was cold. At the same setting of 24c.
So I guess the hvac also chooses to give warm/hot air according to the outside temperature.. (also, regardless of the outside temp, if I set to 23c I would always get cold air)

before I went to the dealership I also checked the actuator motors, and unplugged and plugged back in the one behind the instrument cluster, since that was the one that made the clicking noise. Apparently if you disconnect and connect it back, it will reset itself, its position, from what I read across different forums. Furthermore, the clicking noise disappeared when I disconnected the battery as I mentioned in an earlier post, so indeed it will reset.

still don’t know why there was that ticking noise in the first place, since the stepper motor is fine?

tl:dr -> disconnect/reconnect battery and interior temperature sensor near instrument cluster was bad