[W126 Coupe] "Popcorn Sounds" behind the climate control panel

[Dick Spellman]

Well, I just replaced the acc head unit in the 86 sedan last weekend 
with a rebuilt unit from <http://www.benz-store.com/> (ask for Ken).  
Cost was $155 with 3 year warranty and $50 core charge.  Installation 
requires that you confirm there is no dead short on either the 
mono-valve and/or recirculating pumps before installing the new unit.  
Failure to do so voids the warranty.  Also on the new unit, be sure and 
press the two bulbs on the face into there sockets before covering with 
tape to be sure they didn't become disturbed during shipment.  A whole 
lot easier to confirm with headlamp switch ON that they are working 
before re-assembly of the wood veneer and center console. (Don't ask me 
how I know this).

Replacement was for a variety of malfunctions and one of these while a 
nuisance was the 'clickety-clack' or chatter of one or more relays that 
moving the temp dial up or down a thumbs distance would sometimes clear 
or changing button selections for a brief period.  In the end, I had 
both blower motor speed and air direction going haywire and much of this 
I attributed to hitting bumps in the road that would send the unit into 
a tizzy.

To sum it up, water bubbles sounds could well be the recirc pump pushing 
a bit of air and a fairly loud clickety-clack is probably the head unit 
on the way out although I lived with mine for 6 months or more so long 
as things appeared to work as ususal and the dial or button change 
cleared the chatter.

Dick

mavris2 at comcast.net wrote:

>Henry, 
>
>If its what Dick has descirbed then thats probably it.  However, if you are hearing a every now and then pop, tick noise from the climate unit, its probably a sign that you push button climate unit is on its way out.  At least that is what mine did. More like a clicking noise for quite a while. It would work and did not always make a noise.  Then it finaly gave out :(   
>
>Jason 
> -------------- Original message ----------------------
>From: Dick Spellman <spell.yy at verizon.net>
>  
>
>>Hi Henry:
>>
>>If this is the first time in a while since the car has been driven and 
>>you are calling for heat vs cool, the sound could be the auxiliary water 
>>pump pushing coolant through the heater core and a bit of air could be 
>>trapped in the system from a prolonged period of no use.
>>
>>I've heard it and it does go away with a bit of continued use and time 
>>while in the heat mode (ECON with inside temp request higher than cabin 
>>temp)
>>
>>Dick
>>
>>Henry Viveiros wrote:
>>
>>    
>>
>>>My wife's 1986 560 SEC has sounds similar to popping corn behind the climate
>>>control panel. Maybe it sounds like "water bubbles"?. Anyone have any ideas
>>>about what it might be?
>>> 
>>>
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>>The MB Coupes Website!
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>
>
>The MB Coupes Website!
>W126 SEC Mailing List
>Postings remain property of MB Coupes, L.L.C.
>
>  
>