Here is the deal.

when stopped with the engine running (regardless if I am in gear or not), I can hear a tikcing noise...like a clock......which seems to be coming from somewhere behind the center A/C vents or behind the radio...(ya know that area....in the middle)...

When I put my hand on that area...I can feel it pulsating as it ticks...

It is a tick that comes on every 5 seconds ONLY when my A/C or heater is on (and both work A okay....actually the A/C is more like a freezer, and the heater...will get you sweating)....

Very weird thing!!..

My car is a 1996 C220, 74K miles.

I would appreciate any ideas.....no matter how weird they are...they will not be weirder than the problem itself.

I have a similar slow "ticking" that is audible and transmitted through my steering. It is only when the A/C is on, and felt only when idling. It occurs when my thermostat is set on less than maximum cold, and happens on a cold day when the A/C compressor kicks off. I have located it to a ?solenoid switch which regulates the heating. When the thermostat is activated, it switches the A/C compressor and activates this switch which then causes this clicking sound. Being in the tropics, my heating system has been disabled (hot water inflow and outflow blocked-up and excluded), a common practise here.

However, I am not sure if this 126 system is applicable to your model, although the 5-sec interval sounds remarkably similar. I hope this helps.

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1983 w126 280SE - daily drive
1983 w123 200 - sold

I am not sure either....

but thanks for your reply kennysin......hopefully this thread will lead somewhere......and that somewhere being anywhere.

A piece...of what over where????

what r u talking about.......

Are u telling me to forget about it...

Or are u eluding that I tape something ..if this is the case ...then what exactly am I taping.

I'd put a piece of tape over the tick and forget about it.

so where are all these mechanical minds??!

come out , come out ..wherever you are!!??

I read somewhere on the forum that it was the monovalve for the climate control

yeah I read that too ...but I don;t know if this is true for my car.....and if it is true...can anyone provide me with any instructions as to how to reach the monovalve, to fix it or replace it.

Thanks in advance

Get a shirt that says "Bomb Squad" on the front, and "If you see me running, try to keep up."

















THEN START RUNNING!!!! :p :p

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http://comp.uark.edu/~dmgill/signature.jpg

what an idea.........?!!!

come on ....let's be serious for a second here?!

Any legite' ideas out there??

The 190e has the same ticking .... I am glad you posted this. I am curious as well as to why and where it is coming from.

Anybody encounter this before?

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Yes, the mono valve is a noisy little guy on w202 c-classes.
It is normal. There are no "factory" fixes. However, Some people
have been known to re-mount them with different materials.
Sadly, it is the coolant that transmits the thumping and the heater
core and box amplify the noise.
Dr.D

Dr D....thank you for your reply.....can U advise me of a way any way to be able to minimize that noise since it is normal.

You mentioned some people were able to fix it ...or at least minimize it, how?

and what is the monovalve and where is it ??

Gentlemen: I had others install new pads on my '97 C280 Sport at around 100K miles. Now I was given a set of kevlar/metal pads and I would like to install them my self. Would any one be so kind as to tell me if this is a complicated job on the W202 car or is it like the DIY section shown for the 320E, which really looks simple. I have heard that the job is easy but would like some sort of cofirmation. Much thanks, and if a silver C280 passes through your car on the way to Florida in January, it might be me. Thanks for any help. fearlessone2@yahoo.com

Guys: I have a C280 car and do not hear this sound. I thought the question was regarding another chassie. I have not heard any ticking coming from my dash. However, after my son cleaned out my computer, I notice that my question regarding brakes is now shown in the discussion. In any event, sorry about this, but I still would like to have some help regarding replacing brake pads on my W202. Thanks and sorry for the digression of an interesring subject. PF