Is there anyway to bypass the climate control on my 1978 300D so I may get heat from the heater core, so in the winter I can have heat? Currently I have no heat or A/C in the car. I am thinking a way to bypass the system and have a manual adjustment of the blend doors?

I've seen threads where folks added a manual cable-controlled valve to control the heat. I didn't pay a lot of attention to them as my system works right now. But the threads are around either here or at benzworld.

Good luck

__________________
Baton Rouge, LA
1977 300D Non-Turbo

There are a couple ways to go here.

The service manual is online. The system was actually designed by Chrysler. It's worth a read just for the retro cool factor.

There are replacement servos out there but they are expensive.

Another approach is to find a 240D in a junk yard and swap in the manual system. This is the most stock looking option because the component mount points are there already.

Here is a thread one guy did on putting a valve to replace the Servo.

It's heater season! ACC fun...

This is the Chrysler manual on the Servo.

1971 Imperial & Chrysler Auto-Temp II Service Book (Session 281) from Master Technician Service Conference

Additional info.

https://s3.amazonaws.com/sspublicweb/mercedes/Mercedes+116+Climate+Control+Service+Manual.pdf

https://s3.amazonaws.com/sspublicweb/mercedes/83-604+climate+vacuum+diagrams.pdf

https://s3.amazonaws.com/sspublicweb/mercedes/w116-vacuum-climate.png


Replacing the Type II system you have with a Type I manual system as a 240D used would be the best bet. It has been done. Just have to remove the dash and remove the AC/Heater control box from one to the other. The shape of the boxes are exactly the same and will swap over. You will have to then hook the electrical together, add the Water Valve on the Fire Wall.

Climate Control conversion editorial coming in the near future

this is a very good detailed write up by DMORRISON.

PeachPartsWiki: Replacing the A/C Evaporator

There are other threads on this subject over the years.
Hope this helps you some.


I have pulled4 on these AC/Heater boxes out of 240D`s in the PNP`s. not a bad job to do, but is a good place to learn how to remove things w/o breaking things. just label the wires the best you can as you remove things.
A whole box with everything, heater core, Evaporator and heater blower will run in the $60 range.

I keep threatening my 85 300D she is getting one of these installed.


Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

As already explained, you need to look at the original functionality manual to understand how the system works. It seems complicated, but it was probably the high point of tech when it was designed circa 1972.

Here is the original Chrysler manual. Your control panel looks different but the system is basically the same: 1971 Chrysler Imperial Auto-Temp 2 Service Reference Guide - Session 281

Don't ditch the system until you at least understand what it is. Once worked through, that system is as reliable as any other. My first 300sd had it and I didn't touch it for the 8 years I owned it.

I cannot type their name in a post to this list, but the online vendor whose name is similar to Mercedes Sauce has two videos for going through this system. I believe one is free and you pay for the second. They are actually very good and provide some info you won't find on the forums.

If you don't want to troubleshoot the system, you can simply install a conventional heater valve, one with push/pull cable control. This can be done even with the servo still in place. This will get you temperature control.

I have never seen a solution to installing something to control the system flaps manually, though several people over the years have announced they would try. People who install the manual solution for the temp generally just set the flaps where they want them and live with it.

Here is one discussion: Climate Control Servo removal Auto Temp II AC 1980 300D

There is a website somewhere with a photo DIY of installing a manual valve, but I cannot find it just now. It isn't rocket science, you just need an appropriate valve (older Toyota ones are good), a choke cable long enough to get to the cabin, and some way to anchor the cable pull inside the car.

EDIT: Ok, looks like Charlie and I were typing at the same time, and he types faster. Looks like he has better links....

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Here's another: early W123 servo bypass described/pics

__________________
Baton Rouge, LA
1977 300D Non-Turbo

Easiest is to install a manual shut-off valve in the 5/8" heater hose. One location is where the aux pump sits (if in 1978), and good to get rid of that evil device anyway. I am guessing you just need a summer/winter swap, so lifting the hood isn't an issue.

If you want cabin control, most heater shut-offs are vacuum operated (one tube, spring return). I bought a few plastic ones cheap (~$10) for my 60's cars. You can get vacuum solenoid valves in 1980's cars (emissions, I know Chryslers had many and I have a cute little one from a Porsche). You then just need install a cabin 12 V switch to actuate the solenoid.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I would recommend if the body of the servo is Bakelite and cracked....as they did....to not even fool with attempting to added anything....because these are known to crack, leak and then cause coolant leak...thus killing your motor.....also the servo is know to stay "On" and kill your battery after sitting for two days...ask how I know..

When this system works, it is very fun and it works quite well....but getting it working...well that is fun...keeping it working is even funnier....

My recommendation is to buy the unwired kit....replace the aux water pump and fuse it as this is usually the first nail in the coffin....then I would replace the temp sensor tube and check all the flaps to insure none are torn...

You'll then end up with working heat for probably 5-800$....then you will be able to move fourth with getting the air conditioning working...

https://unwiredtools.com/accii.asp

I need to fix mine again and I refuse to pay that money....so one millennium I want to attempt to make n sell their type of kit for cheaper....mainly because their fix does not allow the fresh air flap to work....thus you only get recycled cabin air...

__________________

There is no easy way out with this system. Putting in manual valve is okay if you live somewhere where you don't have a need to switch between full defrost and full heat. It is possible to wire that solution up so you have AC.

The Unwired solution doesn't work unless your vacuum system is in full working order. So you have to get that sorted, then their system isn't exactly cheap. People who have installed it have given mixed reviews.

What's beyond me is why, in all the years I have been reading posts on this system, no one has ever written a plain-language step by step guide to going through it, end to end. The Mercedes Sauce video I mentioned earlier comes close but it's a discussion by the narrator holding the components in hand seated at a bench. A manual would be nice.

If you look up the ACC section in the factory manual, it outlines a procedure for testing it. It's actually as close to plain language as the factory manuals get.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I honestly don't think there is any way to write a simple guide. I could take photos of the items known to go bad as I am having issues with the system again but there are so many items that can go bad for so many different people..

What happen with my system is that the AUX water froze thus frying the amplifier/computer and then taking out the servo. I had also noticed my temp sensor tube was bad and needed to be replaced.

Now on my car every vacuum accessory still works and all of them still have the original to the car diaphragms....but so many other people have issues that also involve the pods in the dash or bad vacuum pump diaphragm.

The issue is that it isn't some crappy climate control system brought to us buy Chyrslers...its the fact that at the time they were attempting to create an automatic system that was way ahead of their technology at the time....thus the system incorporated the technology they had at the time and they made it extremely complicated in order to do what it needed to do...

The issue was that that technology life span was limited and regardless of miles some people saw five years of service from this amazing technological climate control system...

__________________

It's not that hard to swap in a manual system from a 240d - I did that on an '80 model coupe; added Rollguy's Sanden conversion and now have a very nice and easy to use and maintain system. I've pulled a couple more manual boxes at the yards for future use; that is a good way to start/ learn what you're getting in to. Also I suggest you pull the wiring harness (keeping it intact) all the way back to the fuse box and up around the drier and the aux fan - it's totally different.