450SL Servo Bypass setup w/ pic - how bad is this?
 

After seeing the picture, I hope that most of you aren’t staring at your monitor with your hand covering your mouth, because you know how bad this set up is for the car.

Anyways, this is the current bypass I have setup in my 1980 450SL. My servo broke a few years back, causing a constant battery drain on the car, so after finally tracking down the problem, I removed the servo completely and just bypassed it by connecting the hoses that ran into the bottom of it with copper tubes. I have not had any problems with this, except for the fact that it constantly blowing hot air into the car and I live in Texas. It was fine over the winter, but I would really like to have some cold air blowing into the car, even if I’m not able to control speed or temperature.

Based on the setup I have in the picture, is there a way I can reconnect or add any hoses or valves to get cold air to pump into the cabin? I would like to do the whole digital upgrade kit for the servo, but I don’t have the dough right now, so I’m trying to get by with what I can.

Any help is appreciated.

Thanks!

if youre not worried about having your vents work correctly, you can just install a 190E heater shutoff valve in place of one of those copper tubes (you'll have to figure out which one). apply vacuum to it when you want cool air inside the car.

For now, get the directions from unwired tools for the digital servo kit and read over how they setup the system when the servo is gone, should find some useful info in there. They use the same shutoff valve in place of the servo.

I used the unwired tools diagrams to fix a vacuum leak in my servo system... This system looks more difficult on paper than it actually is. I bought a used servo and put it in, my sensor chain was working and the servo motor ran. But I had a leak that didn't have the blower working, I took out the glovebox and found the "fresh air flap" element was ruptured. I plugged the line and now I have a completely working ACC2 system. You can get the rebuilt servo for $450 from germanstar, or used ones on eBay for $120. Unless every vacuum line is crumbling from age in the car I suggest keeping the ACC2 system.

Or, remove the glovebox and simply wedge the center vents open, run a heater valve and cable to the cab or use the vacuum heater valve.

Thanks for that input, as well.

I've seen a lot of people talking about heater valves and cables, etc. Can someone give me a little bit more info on that? What exactly are you talking about doing, and are there any links/pics that help explain it?

As I was going through my manual and a number of posts yesterday, just trying to understand more about the system as a whole, I realized that pretty much all that is discusses is the flow of hot water through a/the valve into the heater core...the more hot water that goes through, the more heat that flows into the cabin.

What I realized I don't understand and what isn't really addressed is what needs to happen to get cool air to flow into the cabin. Where/when does the air get cooled, and how do those components (the condenser, I imagine) get involved in this? So I pretty much understand the heater side of it, I just want to understand the cooling side of it.

Alright, I finally did it! And it seems to work so far!

In place of the copper tube that runs from the water pump to the heater core, I installed a ball valve so I can manually regulate the flow of coolant into the heater core. When I shut it completely, I am getting the cool air I have wanted for so long.

Here is my question, though. Am I risking any damage to the car by completely closing off this circuit, meaning that the coolant can't pass into the heater core, and then go wherever from there? If I were to claim complete ignorance, I would think that that would eventually cut off coolant from passing through the radiator, causing it to overheat. Or, are these two essentially independent circuits, so even though I am blocking the coolant from passing to the heater core, it is still getting cycled through the radiator?

I just don't want to cause any major damage to the Benzie.

Thanks!