W123 blower regulator basics . . . and not so basics

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Former Member
Mark Pfeifer's picture
Weddington, NC
Joined: September 12th, 2011



If this has been covered elsewhere in the fora, I apologise . . . I searched "blower regulator" and came up empty.

I recently picked up a fairly well preserved W123300D, model year 1978. The car has the classic problem where the climate control has two modes: off, and "full heat full fan defrost".

The previous owner indicated that his MB shop told him that it was not the climate control panel, but the "blower regulator" that was at fault. The PO and the shop are both reliable, so without even dusting off my multi-meter, I purchased one. 

Various tech sources online indicated that its location would be either "behind the glove box liner" or "a foot abaft the headlight on the inside of passenger fender". There is nothing at all resembling this part in either location. I've had the center console and right side interior fascia completely apart and there is nothing at all that even closely resembles this box. Nor is there a barren 'female' connector that could accept the 'male' plug on the back of it.

I'm fairly certain I purchased the correct part (W0133-1605412) because a well known parts supplier's website and EPC both agree on the part number. I'd very much like to install this so that I can have a multi-functional climate control system in this car. Any guidance (pictures help but clear words would work) would be dearly appreciated.

While I"m posting on this subject I'd like to ask a corrollary question . . . 

Everything I've read seems to indicate that the early W123 ACC, while a noble effort given the available technology, is high maintenance, and not very reliable. This is not a car where originality is of the least concern; in fact the simpler and more robust I can make it the better.

Is it possible to retrofit the non-ACC "manual" climate controls from another car, such as a 240D or 230 of the same vintage? 

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1973 450SE 
1978 300D 

Tom Hanson's picture
Arrowhead Farms, CA
Joined: February 20th, 1997


1970 300SEL 6.3
Mark, It might be in your


It might be in your better interests to get the repair manual on cd-rom. We have them in stock. Please contact me at the office. Thanks!


Tom Hanson
Supervisor, Parts Operations
Mercedes-Benz Classic Center USA
949 598-4842 direct.

Prior MB cars: 2010 ML350 Bluetec, 2003 C320 Coupe, 1986 300SDL, 1971 300SEL 6.3, 1973 450SE, 1959 220S, 2011 C300

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