Tickety, tock!

[Malcolmr]

Chaps, I've got an endless tickety tock sound coming from behind the console when the ATC is turned on. It sounds like one of the air direction servos or similar trying to switch something on and off but not being successful and so doing it again. I had a look with a torch recently to see if I could see something moving but no luck. The sound seems to be coming from higher up towards the rear of the heater unit. Anyone got any ideas? It's a bit annoying as it's out of time with "Click go the Shears" on my favourite Aussie CD.

[black olive]

Hi Malcolm.

have a look in the bible, the gospel according to the atc system on P81.
Black olive decrees that the issue may be either the distribution servo motor or the balance valve for the dual climate ATC.

bible can be found here

https://www.two-sixties.co.uk/mgoc260/html/f0rum/showthread.php?t=3348

why do they build the car around the heater system ?

[Martin Warner]

Malcolm. Are you sure it is not one of those Locusts nesting up inside your dashboard. You could always try doing a "Webber" to shake it out.

[Malcolmr]

Nice thought Martin - might pass on the end to end though!! By the way, I can't get the manual to open up. Any suggestions? I'll have a look on the CD while I'm waiting...

[black olive]

its 26mb and takes ages to download. suggest when you are successful save a local copy

[Malcolmr]

Hi Malcolm.

Have a look in the bible, the gospel according to the atc system on P81.
Black olive decrees that the issue may be either the distribution servo motor or the balance valve for the dual climate ATC.

OK - thanks Steve - I find that I have already downloaded the bible at some earlier point so I've read the relevant section but am none the wiser really! So what would be causing one of these servos to be operating continuously? Would it have become disconnected somehow from whatever flap it is trying to operate, and so therefore keeps trying? Everything seems to work correctly with air distribution. And is there some way I could diagnose which one might be playing up before I rip into the dashboard? Would that diagnostic test on the ATC help and perhaps throw up an error code?

[Contemporary]

Malcolm,

These may also be worth a look:

http://www.the75andztclub.co.uk/forum/showthread.php?t=32374

http://www.the75andztclub.co.uk/forum/showthread.php?t=5979

hth

[black olive]

dont know malcolm, I know mine clicks and groans when switching on and off the ignition, I just put it down to being alive :D

[Malcolmr]

Thanks again chaps. I ran the diagnostic procedure - no result. The tickety tock is only there when the ATC is on AND the engine running. But...it is definitely the balance valve because I managed to make it stop by changing the balance. I guess I normally have the temp set the same on both sides of the car. But if I adjust it so that there is more than 2 degrees difference, the tickety tock stops. And as I adjust either temp setting, you can hear the valve operating with the same noise. Don't know why it keeps operating when the temps are the same. Interesting...

So it looks like she will have to sit in the cold while I enjoy optimum temperature! And at least I can listen to the locusts in peace.

[black olive]

glad you have found the source of the noise. as the balance valve is part of a servo loop system, it will keep constantly readjusting itself dependent upon the temperature inputs.

[Malcolmr]

It's started up again, so that confirms that it is in a loop. I've now set her temp to Lo and it's stopped again, but I know she won't last long like that!! If it really drives me mad, can I disconnect the balance valve servo, do you think? Or will the whole ATC have a spak attack?

[black olive]

I wonder if the valve body is sticking. Im dreading the first request to " black olive" this valve, as firstly it has a very tight space envelope due to its position, and secondly, I'm not sure the design of the diverter valve I use would lend itself to the application.

I'm not convinced of the "benefits" of a dual climate control system, and to be honest would replace the whole shooting match with a 15mm t piece, dont know whether this would upset the panel's diagnostics though. Other option would be just to unplug the servo as you said, and see what happens- easier than fittign a t piece

[Malcolmr]

Thanks Steve - I'll report back later on what I do next!