Bypassed ACII on my W123
 

After the AC11 finally completely quit (no hot water for defrost), and this after the PO replaced the whole works with fancy new stuff just a few years ago, after which it quickly defaulted to defrost only, I finally took the plunge today and ripped out my ACII and simply plugged the coolant lines right into the heat exchanger. Living here in the Salish Sea, it is never too hot (at least not for someone who grew up in SoCal) and so AC was disconnected long ago. And, it is never bitter cold here. So the only function I really need is to defrost, and that is what she now does admirably.

On this and other forums I've read some question as to whether the little electric circulating pump is necessary for hot air when idling, and let me add my voice to those who speak from experience saying it is not. My defrost cranks out the heat at idle just as it does other times.

For anyone else looking to do this, even for a temporary fix, let me tell you that it does not cost a penny, as you can reuse the coolant line from near the firewall to connect the pipes near the front of the engine. One of them is long enough, and you can tell.

I suspect this fix may be permanent on my car, as all I will ever need is defrost, but if I ever feel like I have $ burning a hole in my pocket I may install the manual valve in the line to control the flow of hot water. Doubt I would bother.

What I love most, perhaps, about my 300D is the elegant simplicity of the motor, and it is nice to have ripped out that monstrous AC11 and to have removed an incongruous complexity from an otherwise bombproof and simple vehicle.

What fancy new stuff did the PO replace?

I have all the receipts of them having replaced the servo and the whole thumbdial/button console in the car. I think they might have also replaced the guts behind the glove box. After doing all this, they said it worked for about a month or two before something gave out. Could have been a vacuum leak or who knows. I bought the car around then, and when I drove it away only the hot defrost worked, which was fine with me as I describe above.

I thought about the Unwired tools thing, but you are still victim to the vacuum system and I just don't need the full features of the system enough to spend the $700. No, simple is beautiful, and reliable, and easy to fix.

Thanks. I just did the servo boogie and you're lucky that you don't have to worry about AC. My W116 is a cool ride when the temps are good for windows down :cool: Plus a heater isn't hard to keep running.

Did you have a plastic or aluminum servo?

I'm not entirely sure, but the cap was plastic and the body was aluminum. It had also developed a slow leak of coolant, to add to it's general lack of functioning. And yes, I realize that most any other place I lived would require either a more multi-tasking heating system or AC. But round here, the water is 55 degrees year round and the air is never far from it.

In a general fit of removing stuff that doesn't work and I don't need from the engine compartment, I also removed the old cruise control unit and will soon figure out what I need to do to legally and safely drain the AC of gas and will remove the whole AC system too. Maybe I'll ebay the compressor for the AC, as it is also fairly new.

Gotta love the easier access to what really matters, and that's 5 cylinders of diesel perfection!

Yea, it sounds like you have the upgraded less failure-prone aluminum servo. I just dropped some $$ on upgrading mine so I was interested in your system and what failed.

If you have some more info on how you bypassed the servo, I'd love to know how to do it...I have a faulty servo at present now and all I need is some heat --- don't need A/C.

thanks for any info !

The servo in my 1979 280CE was replaced 7 years ago, its the alum body unit. Knock on wood( burl dash trim), it still works fine, no leaks and regulates temp just fine.