Well I knew I was in trouble when I saw wisps of smoke coming out around the pushbuttons on the climate control unit on my 124. It had been acting up and I figured it was likely going to need replacing but I wasn't anxious to spend the money so I let it go until this happened. Now that it has fully and truly fried itself (nothing works at all) I'm obviously going to need to replace it. Does anyone know if a bad sensor may have caused this and if so which ones are most likely a problem? I have the CD but it shows a special electronic testing box that I doubt I'll ever be able to borrow/rent. Any warnings I should be aware of or should I just plug a rebuilt unit in and hope for the best? Thanks for your feedback.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Be sure and check the auxilliary water pump before putting in a new CCU; perhaps consider a 1 amp. inline fuse on the power input to the pump. Rumor has it that a malfunctioning aux. pump can use the CCU as a "fuse" if it draws too much current.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

jbaj007,

Thanks for the advice about the circulation pump. Mine was siezed! The washer bottle (located right over the pump on the 124s) leaked and the washer solution got into the pump motor. I managed to clean it up and get it going again. I also added a 2amp fuse to the hot lead. I don't have my new CCU yet to try it out but I think this is what caused my original CCU to die. Thanks again for the suggestion.

LRG

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Is the spec for this pump a one or two amp circuit...?
I need to add an inline fuse and wonder if anyone has any experience with this?

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

On the W124 the line runs from an 8 amp fuse in the fusebox. Obviously the draw in my case wasn't enough to blow the 8 amp fuse. I don't think there is a spec for this since MBZ never installed a fuse here. I put in a 2 amp fuse and ran the motor fine without blowing the fuse. You might try it with a 1 amp and if it blows move up to 1-1/2 or 2 amp.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

I'll give that a shot and play with it a little.
I would think there is a spec somewhere for it though.

Guess you saw I bought a 123? I* sometimes ask "Did do the right thing???" My wife is getting better about it anyway
Sometimes you have to wonder about the "deals' we find....


Making it better every day though!

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

As a precaution, I want to do do the above. On an 84 300DT, where is the location of the Auxilliary Water Pump? What color of a wire (power) should I install the fuse?

Thanks for your help.

Is the Auxilliary Water/Coolant Pump aka Circulating Pump?