Manual Climate control swap - PeachParts Mercedes-Benz Forum

crazy4diesel · #1 03-29-2014, 08:45 PM

Hi all, I thought I'd start another thread separate of the project thread to discuss the Manual Climate control swap just in case someone else ever wants to do this there will be a thread discussing it.

I'm moving the manual climate control system from my 82 Euro Spec 300TD to my 83 US Spec 300TD for a number of reasons. A) I love simplicity, and will always favor the more simple system. B) The automatic servo system in the US spec car is in fail-safe mode--IE the defrost only.

I'd like advice on a number of things as I get into this, and hope other's have maybe already have done this project before.

I am operating on the assumption that the most straight forward way to go is swap the entire heater and fan assembly to the US spec car.

First of all, the manual system has three knobs that are attached to large metal switches or valves, which are attached to a bracket that is made of Bakelite and riveted to the heater box. Since every person, I've run into so far has indicated when they have broken into the system they have discovered the same thing I did, that the bracket is broken, I have little hope of finding and intact one, so the options are: A) buying a new one, which I have not been able to find a source, or: B) fix this one, and go forward--most likely solution.

Second issue: Wiring the manual system into the wiring harness of the US spec car. This is a multifaceted question.

1) The air conditioning was not working on the Euro spec car when I bought it, so I don't know how it is supposed to operate. Does the AC compressor kick on when you dial the temperature wheel to "max" in the blue zone?

2) Is it necessary to split the wiring harness of both cars open to accomplish this swap?

I think I have chased on the Euro car the wiring that controls the AC compressor. But, finding the "like" wires on the US car seems daunting because they are part of the servo unit, and immediately travel into a massive bulk of harness.

I have not been able to chase the wiring on the Euro car that controls the fan. And again, how would I find the matching wires on the US car.

Up front, wiring is NOT my thing, I do have a friend helping though when he has time, that is much better with it.

pj67coll · #2 04-01-2014, 07:09 PM

Quote:

Originally Posted by crazy4diesel

I am operating on the assumption that the most straight forward way to go is swap the entire heater and fan assembly to the US spec car.

I think that is correct.

Quote:

First of all, the manual system has three knobs that are attached to large metal switches or valves, which are attached to a bracket that is made of Bakelite and riveted to the heater box. Since every person, I've run into so far has indicated when they have broken into the system they have discovered the same thing I did, that the bracket is broken, I have little hope of finding and intact one, so the options are: A) buying a new one, which I have not been able to find a source, or: B) fix this one, and go forward--most likely solution.

Yep. When I tried working on my 240D's system I found the same thing. I think repairing it is the best and most practical option. I wasn't able to complete my project but my thoughts are that the best option is to remove everything from the broken Bakelite bracket, glue it back together and then reinforce it with several thin strips of plastic and perhaps aluminum if you can work wit it, cut into a template to fit over the original and glued in place in layers to form a kind of laminated structure that should be stronger than the original.

Quote:

1) The air conditioning was not working on the Euro spec car when I bought it, so I don't know how it is supposed to operate. Does the AC compressor kick on when you dial the temperature wheel to "max" in the blue zone?

Yes it should. However in the euro car switching the AC temperature wheel to Max will only turn on the compressor. No air will blow until you switch on the blower fan using the center wheel which is the blower fan speed switch. The two outside wheels of course are for heat to the left and right side of the car respectively.

[QUOTE]2) Is it necessary to split the wiring harness of both cars open to accomplish this swap?[/QUOTE

That I'm afraid I can't answer.

- Peter.

crazy4diesel · #3 04-01-2014, 07:53 PM

OK, so progress made... I think.

Labeling wires, and unwrapping the main harness so I can isolate the ones that operate the manual climate system. There had been a suggestion to swap the entire cabin wire harness between the two cars...I don't think that's within my skill set, and I do want to keep some things on the US spec car, that don't exist on the Euro car, power windows, power antenna, power mirror...etc. So, the only way I can think of doing this is label and pull the wiring related to the climate control move it to the US car.

Labeled ever connector, wire and bulb I pulled from the dash of the Euro car. Quite the mess isn't it?

Here the only wires that remain, are those attached to the heater box, and will come out with the heater box. There is one, that's clearly a sensor, but it's really in the heater box tight, and I don't want to pull to hard to release it.

Here is the heater box out, and one the driveway.

Now the big debate, do I split it, and clean the evaporator, or do I replace the evaporator, and the heater core? If I replace them, do I use OEM units or Ebay units that are a fraction of the price...any experience here is appreciated. The water coming out of the heater core was very rusty.

cfh · #4 04-01-2014, 08:17 PM

Absolutely open up the box, clean it out, and take the heater coil and evaporator to a radiator shop to test, clean and repair those. I did a swap just like this but made the mistake of not testing the heater coil - and it has a slight leak. (I was so excited to get the ac working at the time, that the heater did not even cross my mind).

The wiring is an adventure - I ended up with quite a few redundant wires just taped off.

crazy4diesel · #5 04-01-2014, 08:21 PM

Quote:

Originally Posted by cfh

Absolutely open up the box, clean it out, and take the heater coil and evaporator to a radiator shop to test, clean and repair those. I did a swap just like this but made the mistake of not testing the heater coil - and it has a slight leak. (I was so excited to get the ac working at the time, that the heater did not even cross my mind).

The wiring is an adventure - I ended up with quite a few redundant wires just taped off.

YEAH! Finally, someone who'd done this. You're experience will be invaluable. Do, I have the process right in theory? I am not remotely and electrician (I turn off the main breaker to replace a switch in the house).

crazy4diesel · #6 04-01-2014, 08:22 PM

I did find this schematic for the ACC system, does anyone know where I might find the same for the manual system?

cfh · #7 04-02-2014, 01:59 AM

The way I approached it was to get the manual system insalled the way it came without regard to integration with the "evil servo" system my car came with - basically it was an overlay rather than a splice; that's why I ended up with redundant wires I just taped off. Like you, I am no electrician and I'm sure there are others who could do this much more neatly. It does work, though.

daw_two · #8 04-02-2014, 05:10 PM

Quote:

Originally Posted by crazy4diesel

Now the big debate, do I split it, and clean the evaporator, or do I replace the evaporator, and the heater core? If I replace them, do I use OEM units or Ebay units that are a fraction of the price...any experience here is appreciated. The water coming out of the heater core was very rusty.

You DEFINITELY want to open up and clean the evaporator!!!!! Here's some pics from my thread at: http://www.peachparts.com/shopforum/3118947-post61.html

Last night's project
Here's the link to ALL the pics I took last night; re-assembly is the reverse order. HA HA. How To Disassemble A W123 Manual Airbox Photos by daw_two | Photobucket <--- I hate PhotoBucket now.....

Took the manual airbox apart last night to clean the AC evaporator and hopefully put it all back together today. Yes, that's the heater core to the far left; AC evaporator in the middle of the pic. Second glass of Chardonnay to the far right....please note it's not empty either.
Here's what it looks like right now:

I think there was more crud on this one then on either of the Dave Morrison's evaporators. Thanks, Dave, for the excellent DIY write-up and also thanks to this forum for continued support.

During cleaning of the evaporator, it almost seemed like I was skinning a catfish --- that layer you see me pulling off was quite tough.

84-300dee · #9 04-21-2015, 11:50 PM

crazy4diesel, did you ever finish the swap?

I am attempting the same. See below thread for 240d wiring diagram:

http://www.peachparts.com/shopforum/diesel-discussion/366940-w123-auto-manual-climate-control-swap-wiring-help.html

charmalu · #10 04-22-2015, 01:02 AM

His last activity was 12-03-14.

Might want to e-mail him.

Charlie