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#1
06-21-2003, 02:46 PM
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230.6 (W114) A/C blower switch
My 230.6 has air-cond, not sure if it's fitted at factory
 The system brokedown. It started with this... There are 4-notch to turn clockwise on the blower switch: 0-1-2-3 (max speed). The switch seemed not workin' on "2", therefore it had only slow or fast speed blowing. It worked fine for the past year. One day, when turning the knob, no cool air blowing out  , but heard the A/C compressor clutch still engaged. I didn't use the system for a while, then the compressor clutch no long engaged.So, my first attemp was to remove everything and try to reach the blower switch. The switch seems complicated (to me). I tried cleaning contact, plugs/sockets with WD40, won't work at all. The blower switch end seems not easy to be removed!? I even loosened the centre console, just in case need to check the thermostat dial (but don't know what to do w/ it ) I tried to directly wire 12V to the compressor clutch, it works. Now, I have no clue where I should check further to make the system work again. Please advise further diagnosis. THANKS in advance!
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'74 W114 230.6 '87 W201 190E 2.3-16 '97 W210 E320 Avantgarde 
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#8
06-21-2003, 03:56 PM
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The original blower switch was riveted to the lever assembly. I would be amazed if yours was still original. They last a shorter and shorter time as the blowers get old and draw to much current.
They fail because the mmetal contacts get so hot they melt their way into the plastic backing releasing the tention on the contacts increasing the heat untill they don't work. I have probably diagnosed that system a thousand times and wouldn't think of doing so without a wiring diagram. What is really confusing is that the switch works differently depending on whether you are in A/C or heat mode.
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Steve Brotherton Continental Imports Gainesville FL Bosch Master, ASE Master, L1 33 years MB technician
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#9
06-21-2003, 08:07 PM
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If your '74 230 is like my '72 W114 250, your heater and AC use 2 separate fans. Your AC thermostat is connected, via vacuum hoses, to a vacuum operated, blower change-over switch, located above the accelerator pedal.
Does your fan switch still operate the heater fan OK when your AC thermostat knob is turned all the way off? If so, it's probably not the fan switch. I agree with Steve, you should get a wiring diagram. If you decide to replace the fan switch, you should be able to unscrew the heater/fan control panel and pull it out far enough to reach the fan switch. Happy Motoring, Mark
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DrDKW
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#10
06-22-2003, 06:14 AM
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Thanks so much for the helpful tips.
I never notice if my car's heater is working (as HK is too warm). But for sure that the fan doesn't work no matter the "colder" knob is on or off. And I also noticed that the blower switch is not riveted to the lever-assembly. It's attached to it by 2 pins. I agree it's wise to learn more from the wiring diagram, but where can I get one? And website provide such info? Pls advise if anyone knows. Many many thanks!
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'74 W114 230.6 '87 W201 190E 2.3-16 '97 W210 E320 Avantgarde
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#11
06-22-2003, 10:50 AM
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Have you checked with a volt-meter or 12 volt test-probe to see if you have power to any of the ac or fan wires or connections you have exposed? You said that nothing is working now. Have you checked the fuses? Even if the fuses look OK, they could be loose or corroded in their sockets. Check them too with a volt-meter or test-light.
As for manuals, Haynes has a Mercedes 230/250/280 repair manual with some wiring diagrams, tht may still be availible through book sellers, either in your area or online. The Haynes manuals and the Mercedes factory W114 manuals sometimes come up on Ebay. I think the Mercedes manuals are also still availible on CD. Happy Motoring, Mark
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DrDKW
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Linear Mode
