Author Topic: 1st Gen Mercedes ACCII Climate Control Servo: Less Expensive Replacement Option  (Read 5231 times)


  • Vintage
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  • Posts: 623
  • Assimilated. Resistance is futile.
  • Location: Salt Lake City, Utah
Yeah, it's a fact of life that the ACCII system on the W116 is going to cause problems and repairs can be tedious. I think this setup is the way to go. Good for the seller for coming up with this design which greatly simplifies the system and makes it more reliable. Of course, I'd recommend converting to manual climate control, but that is such a huge undertaking in itself that it's not realistic for the average owner. If I were to have kept my ACCII, this is the way I would have gone. It seems the worst that could happen is the circuit board fries. In that case, it should be able to have the bad components replaced. Even then, I suspect it would last much longer than even an aluminum bodied servo.
And to be clear - it seems that the "average owner," if this board is representative of anything, tends to be a pretty hard core enthusiast.   
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0


  • Newbie
  • Posts: 9
  • W116 Enthusiast
  • Location: Raleigh NC
Guys I don't want to be rude, but I think for this price this unit represents a fat bargain.  I get that we all want to pinch the pennies, but really the questions and grilling on this unit might have driven the developer away.  I mean do you really expect the seller to support this part into perpetuity?  If my ACC goes tits up I will for sure seek out this kind of setup.  Even if it does not work after a few years, it is still better than than you had with an inop ACC unit, no?  Granted, I live in a fairly mild climate, thus a perfectly working HVAC unit is not high on my list so I get why some of you are quite anal about this, I just think that it might be time to calibrate your expectations a bit here.
Friday rant over 8)

Daantjie, I appreciate your consideration of both sides.

I didn't realize this forum post was still moving along (so I haven't been active in a while on this site), and I want to make clear that I am here for any help/ support in the future.

I have sold a significant number of units now to many different places across the US, Canada, and some countries in Europe--which was only possible with the help, questions, and tough advice from you guys. So far, every customer has gotten their unit up and running in their car. A handful of customers had initial difficulty in getting the unit installed, but with my guidance, they were able to overcome that and all the units shipped are currently functional.

Responding to xaliscomex, each unit contains three solenoid valves to direct the vacuum that are very expensive and tough to manufacture because they are medical-grade and designed to last for hundreds of millions of cycles. These solenoids are the biggest expense in a given unit, but also the most reliable part. Thus, if you were to face some failure 1, 5, or even 7 years out, it would be likely that these solenoids could be reused, which would result in a relatively low cost of repair.

As always, I really appreciate any questions + comments you guys have on the kit! Feel free to reach out to me personally as well if you need anything.

Diesel 617

  • Classic
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  • Posts: 233
  • Location: Illinois
Just ordered a kit, excited for it to arrive! Hopefully it breaks 40 next week.
X3 1980 300SD Blown Heads, trans -Retired
1980 450SEL Parted out/Scrap
1980 450SEL to Diesel Parted Out/Scrap
1979 280SE Euro Spec Cloth Seats Sold
1979 300CD Daily Driver - Sold

Inventory of w116 Parts


  • Newbie
  • Posts: 8
  • W116 Enthusiast
  • Location: North Vancouver, BC
Just ordered a kit, excited for it to arrive! Hopefully it breaks 40 next week.

May I ask how well it works? I'm thinking to order this one myself.


  • Newbie
  • Posts: 8
  • W116 Enthusiast
  • Location: North Vancouver, BC
I have been running this setup for 6 months. I have to say it%u2019s not perfect, but it%u2019s better than a non functional system.

My friend also ordered a unit for his car and it%u2019s ok. I wouldn%u2019t say the ACC2 system was great to begin with and also my car may have another issue compounding some struggles as well.

I made an installation video if anybody wishes to see:


  • Enthusiast
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  • Posts: 19
Appreciate the time you took to film the video.