If any of you have owned an old Mercedes W123, you know of the dread heater vacuum servo of death that never works and costs mucho dinero to replace.
Looks like this (middle finger can also be found in the FSM diagram):
Most common work around seems to be to retrofit the manual heater system from a 240d. I really don't like this idea, as it requires total removal of the heater core and surrounding (15 hour job), removal of the whole dash, and a ton of other E36 M3 that no one wants to do.
So I've been thinking of another work around that's a little more GRM friendly (cough jerry rigged cough). I'm thinking about running 12v from the fuse box to a switch that both turns on the aux water pump and opens a butterfly valve to let water into the heater core, and just a rotary switch for the blower motor. Problems? No real chance at AC (don't care), auto climate control (Never worked to begin with), no vent selection (ehhh, but I can live with it). Mercedes purists call the idea "corruption" and "blasphemy" and shout for drawing and quartering. I think it's a fine idea. Holes in my logic?
Can't help you with the Benz, I whole heartily concur with that finger gesture towards euro-car automatic climate control. The ACC system was the one thing that I truly hated in all my SAAB 9000s. I'm glad that my Bimmer has a much more conventional system.
If is isn't using the heater as bypass or anything like that, you could just put a manual valve in the engine bay and shut it off during warm weather.
In reply to Kenny_McCormic:
Part of it is that I'm not sure why there's an aux water pump. I thought about a switch for the aux water pump and a manual pull cable for a valve, but I'm not sure if there would be an issue with having the aux water pump on and the manual valve closed.
Also, why no Mercedes love on this forum?
In reply to RoughandReady:
Well, you DID post at 6PM on a Friday night and expect responses by midnight...
In reply to SlickDizzy:
Haha, I didn't mean that. I just mean that I don't see any posts about Mercedes on this board.
This thread makes me laugh. You can thank chrysler for that lovely piece. If it were me I would do the 240D manual swap. Removing the dash isn't bad, it took me about 3 hours to swap a dash in my w123 the first time I did it. I have a spare climate control unit on my shelf if you want it to experiment on, heck it might even work. (Hahaha,fat chance.) Yours for shipping.
The aux water pump is for heater action at idle when the engine pump isn't moving enough flow.
In reply to bgkast:
Do you know what it is inside these that fails so often? I wonder if they're repairable.
No, I've never dug into one.
Those things are yet another reason a Mercedes will never darken my driveway. They are not very well sealed internally and will corrode badly plus the plastic parts warp. There is someone out there making a CNC aluminum version that does not work well, it makes up for that by being expensive. At one time there was another company making a retrofit which was much less expensive but was a cast iron bitch to install. If I recall the name of the company I'll post it.
