[W126 Coupe] Heater stuck in "on" position

[Waldemar Kalinowski]

Hello Dick,
Thanks so much for your help. It was the # 5 fuse. Simple, if it does not 
happen again. Your very helpful and detailed description will be put into my 
repair files. Thanks again.
Waldemar

>From: Dick Spellman <spell.yy at verizon.net>
>Reply-To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>Subject: Re: [W126 Coupe] Heater stuck in "on" position
>Date: Fri, 09 Jun 2006 08:22:39 -0400
>
>Hi Waldemar:
>
>ACC power - I'd simply replace or swap fuse #5 in the big fuse box on the 
>left side (driver's US side) (should be white and 8 amps rated) It does not 
>matter if the fuse looks good, be sure and replace or swap since a visual 
>check of the fuses does not always work.  # 5 is for power to the climate 
>control push button unit.
>Blower power -  Look for a black harness  going in and out of a flat black 
>holder attached to the engine firewall on the driver's side just in front 
>of the fuse box and brake master cylinder/booster.  Under the cover is a 
>foil fuse (available from MB dealer and <$3 US) that provides power to the 
>blower.
>
>Regards,
>
>Dick
>
>Waldemar Kalinowski wrote:
>
>>
>>Hi Dick,
>>Thanks for quick response. This is a new problem and since it started few 
>>days ago it is constant. It is definitely hot engine air that's coming in 
>>through the vents. Could you let me know where the recspected fuses are 
>>located?  Since none of the climate controls are responding, I can not 
>>change any AC settings.
>>Thanks,
>>Waldemar
>>
>>>From: Dick Spellman <spell.yy at verizon.net>
>>>Reply-To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>>>To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>>>Subject: Re: [W126 Coupe] Heater stuck in "on" position
>>>Date: Wed, 07 Jun 2006 21:26:15 -0400
>>>
>>>Hi Waldemar:
>>>
>>>I'd start with a check of the external foil fuse for the blower and the 
>>>fuse for the ACC.  Next would be the ignition switch.  Is this a constant 
>>>problem or is it sporadic?  For ex. one day you turn on the ignition and 
>>>everything works and the next day you turn the ignition and the ACC is 
>>>dead?  This would be a symptom of the ignition switch failing.  Next 
>>>might be bad solder joints on the ACC head unit harness pins.   Then 
>>>there is the question, does the AC clutch engage for air conditioning and 
>>>you still get hot air?  Then, I'd check the mono-valve which may be stuck 
>>>in the open position allowing engine coolant to flow through the heater 
>>>core and compete with the AC evaporator.   One way to clear this would be 
>>>to place the ACC in MAX AC and see if the stuck mono valve plunger frees 
>>>up.  You could try tapping the mono-valve head as well while in Max AC.  
>>>Last would be the vacuum elements that could allow too much outside air 
>>>to enter the cabin through the fresh air door, defeating the benefit of 
>>>the AC.
>>>
>>>Dick
>>>
>>>Waldemar Kalinowski wrote:
>>>
>>>>Hi Everyone,
>>>>Heater pumps hot air through the interior vents. Heater blower 
>>>>non-functioning.  None of the climate control buttons work. What would 
>>>>be the order of things to check out? How to disconnect the heater, at 
>>>>least temprarily?. Weather's getting hot in So Cal.
>>>>Thanks for advice.
>>>>Waldemar 1989 560 SEC
>>>>
>>>>
>>>>The MB Coupes Website!
>>>>W126 SEC Mailing List
>>>>Postings remain property of MB Coupes, L.L.C.
>>>>
>>>The MB Coupes Website!
>>>W126 SEC Mailing List
>>>Postings remain property of MB Coupes, L.L.C.
>>
>>
>>
>>The MB Coupes Website!
>>W126 SEC Mailing List
>>Postings remain property of MB Coupes, L.L.C.
>>
>The MB Coupes Website!
>W126 SEC Mailing List
>Postings remain property of MB Coupes, L.L.C.