I've had a string of problems with the A/C in my 1993 400SEL. It's like the blower motor is smoking crack. It won't come on at all, then suddenly it's blowing full blast. Then for no apparent reason, it'll quit all together.

After reading some of the posts, I figured it was either a faulty temp sensor or a bad control unit. I changed the control unit, and have the sensor on order.

Then today, the blower won't quit even when I turn off the engine and pull out the key. What's that all about? I ended up disconnecting the plug at the blower to make it quit so the battery wouldn't drain.

blower regulator.


Joe

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Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364

Does the "rest" light(A/C pushbutton) stay on when the key is removed? IF so then the problem is in the control unit itself. IF not then the problem is the "blower regulator".

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thanks guys. The REST button does not stay lit, so I'll be replacing the regulator. Anyone know where it is? Anyone know where I can get a shop manual for the W140? Everyone I've spoken to says it's never been published.

The regulator is on top of the blower which is easily accessed under the black plastic cover at the base of the windshield passenger side (engine compartment).

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks to all. This is an unbelievably helpful forum. I'm reasonably competant mechanically, but I'm new to the MB world and without a shop manual I tend to struggle a bit.

Thanks again. I'll be replacing the regulator tonight.

LOL, I've been wrenching for 20+ years and struggle without shop manuals on a lot of things. :-)



Joe

__________________
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364

Similar problem happened to me. Check it out: complete w/ pics!
A/C blower's output is low . . .

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Regards . . . . JimF
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'94 S500 Cpe

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