Technical Rat-tat-tat noise from inside dashboard

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Technical Rat-tat-tat noise from inside dashboard

BrianMcL

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Hi All,
Even by Croma standards this is a good one!

For exactly 37 seconds after I start the engine a sound that can only be described as a rat-tat-tat comes from inside the dashboard somewhere.

It only started today and happens for 37 seconds every time I've turned on the engine today.

It doesn't happen until I start the engine, (e.g. doesn't happen when I've only got the dashboard lit up), it happens in neutral, first or reverse and irrespective of whether the fan blower is on or off.

And then stops after exactly 37 seconds. Every time. Whether it's idling, going forwards or backwards. Then it stops. Everything seems to work as normal.

There doesn't seem to be any problem with the gearbox, climate control or radio and nothing's fallen inside, at least not recently. The car handles as well as it ever does and there are no warnings on the dash and no fault codes reported.

Has anyone had anything like this before?
 
Sounds like the heater fan. Mine got squeaky once, so I pulled it out and cleaned it with some spirit. Now it's started rattling a bit, but only on fan speed 1.

I'd think the noise only happens on fan speed 1. After it finds a bit of heat in the engine (37 seconds?), it turns the fan up to 2 or 3 and the noise stops.

If you manually adjust the fan speed you should be able to make it go and appear again.

It's under the glovebox if you want to home in on the noise.

I'll probably look for a new one for mine, having read this recently...

http://www.honestjohn.co.uk/carbycar/fiat/croma-2005/?section=bad

"Heater fan motors have been known to short circuit and set the cars on fire."
 
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Hi Doofer,
It doesn't seem top be related to the heater as it makes the noise even when it's off. Also, the tempo doesn't change when I turn the heater up to max.

I'll have a look at the heater thing you've suggested as it sounds like an easy thing to check and can't do any harm.

Merry Christmas everyone, BTW.
 
My little girl does this to but only in winter and only for about 10 minutes on first start up.I thought it was the dashboard warming up an expanding to the inside temp of the her.Must be honest doesnt really bother me that much just a quirk.
 
It might be worth a try to manually select between feet, face and windscreen on the climate control to see if the selector flaps are sticking. Give it a good few seconds between selections to give it chance to make a noise.
 
It is the little control box that operates the temperature on your heater. It is situated in passenger footwell to the left of centre console. My clicks away when you initially switch ignition on, but if temperature control on fully hot it doesn't click. Just living with it as fed up with car
 
Hi All,
Even by Croma standards this is a good one!

For exactly 37 seconds after I start the engine a sound that can only be described as a rat-tat-tat comes from inside the dashboard somewhere.

It only started today and happens for 37 seconds every time I've turned on the engine today.

It doesn't happen until I start the engine, (e.g. doesn't happen when I've only got the dashboard lit up), it happens in neutral, first or reverse and irrespective of whether the fan blower is on or off.

And then stops after exactly 37 seconds. Every time. Whether it's idling, going forwards or backwards. Then it stops. Everything seems to work as normal.

There doesn't seem to be any problem with the gearbox, climate control or radio and nothing's fallen inside, at least not recently. The car handles as well as it ever does and there are no warnings on the dash and no fault codes reported.

Has anyone had anything like this before?

Brian did you stop the rat-tat-tat sound? Like to know your solution because I do have the same rat-tat-tat. Thanks in advance
 
Hi Vento,
Haven't bothered to do anything about it yet but from reading other posts my guess is that it'll most likely be cured by taking out the heater motor / blower unit thing and fixing whatever's wrong with it.

Everything's continued to work fine in the interim but I suppose that's true right up to the moment where it fails completely.
 
Sounds like an actuator over-running and the gears or a clutch skipping/slipping. Either the device the actuator is connected to is jammed or a sensor that tells it got to it's end (home) position has failed. The actuator could be for a heater valve or air control flap. If allowed to continue the skipping parts may wear out.

Robert G8RPI.
 
I agree with Robert G8RPI, sounds like an actuator. Turn blower on high, systematically run through the vents, window, face, floor. But remember there is an actuator for each side, don't assume if the air comes out the drivers side the passenger side is the same.
If its not the vent actuators then it could be the one on the coolant side.
 
Not sure about Vento's but mine does it even when the blower's turned off completely. And then stops for no apparent reason.
 
Not sure about Vento's but mine does it even when the blower's turned off completely. And then stops for no apparent reason.

Pressing button A will influence the degree of rat-tat-tat.
When stationary and switching to airflow re-circulation, the shutter valve behind the pollen filter closes, about 20 rat-tat-tat's are audible.
Switching to automatic, letter A is visible on the screen, no sound is audible.
Switching to fresh air from outside to inside, shutter valve opens, only 2 times the sound is audible.
During driving, only just before car stops and system is on full automatic 20 times rat-tat-tat. Probably the valve closes.
During driving and ventilation on re-circulation, no sound at all.

So most probably the sound is created by the mechanism that moves the shutter valve, don't know how to reach this.
 

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Hi,

any one happen to fix this? Happening in my Croma recently and it's definitely something related to the climate system. When the system is switched to recirculate air it's not producing this rat-rat sound. Only when it's relaying on the outside air.

Help highly appreciated.
 
Hi and welcome to Fiat Forum.
This fault is almost certainly a jmmed recirculation flap / actutor. You would need to inveatigate further. My Croma is RH drive so access will be different.

You can download the electronic service "manual" eLearn from the downloads section here
https://www.fiatforum.com/downloads.php?do=download&downloadid=373
You need to download all 8 parts to a folder run a decompressor (I use 7Zip) to get a .ISO file, make a CD-ROM from that and install from CD.

Robert G8RPI.
 
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