Well, I've searched long and hard and can't find a thread with the answers to my question. Like many, I am having a problem with my climate control. Previous owner has had it fixed before, including a new controller unit for like $1,300 or such. AC is newly recharged and all. PO tells me everything was working fine until very recently.

Only defrost works. Pumps out hot air no problem. No other buttons on my controller do anything. No fan, no anything. No matter the temp setting on the dial.

I know many, many people have faced this problem and someone must have guidance for me!!!

Thanks in advance.

__________________
Where there's a will there's a way
1978 300D

Any climate control help out there? I know a bunch of people know a whole lot more about it than I do!

__________________
Where there's a will there's a way
1978 300D

Unfortunately your problem may be a little hard to diagnose with the limited information you supplied. At the top of your screen there is a tab that says DIY Articles. Click on that then scroll down to AC Diagnosis - this will allow you to systematically test some components. Other than that we can just guess at things like:

Fuse is blown - CCU defaults to heat
Low on Freon -Compressor won't engage
Mono Valve Stuck Open.

The list goes on, but I think you get the idea.

__________________
BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

I haven't messed with my old Chrysler unit in the 300SD, but if the servo is new and functioning properly, the next most likely culprit is the board in the dash behind the glovebox. You may need to consult the manuals or go looking at some Chrysler Imperial website for ca 1971 CC troubleshooting data. It's basically voodoo and witchcraft....

edit- tx's info is not geared toward your unit- you do not have a monovalve as you have the earlier Chrysler designed pos.

Rick

__________________
80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

Sorry you are correct on the mono missed the '78 in the post - had 126 on the brain.

__________________
BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

Sorry if I did not provide enough info. What is that about Chrysler components?

I'm new to MB, but were they sourcing American Chrysler parts back in 1978? That voodoo and magic part is exactly what I have hoped to avoid with this car. I'm just a guy at home with tools and some synapses firing. No shop and no fancy testing equipment! Maybe buying a 1978 was too recent!

My dad has a beautifully pristine 1956 Chevy with 56,000 original miles. Not a single thing on it that we can't fix blindfolded. Want to get there with my 300D, and hope this heater/AC not working problem does not require a trip to the dreaded Indy.

__________________
Where there's a will there's a way
1978 300D

Unfortunately, you found your car before you found us.

Yes, they did use a Chrysler control system on 300Ds from 77 to 80 and 78-80 W116 300SDs (as well as gassers like the SLs in the 70s). They went to an MB made system in 1981 that is somewhat better, but still irksome. The 240D and the euro cars have the most DIY - friendly system. People have fixed a lot of these units by themselves, so it can be done. There is a new electronic version for $600 or so that replaces it.

But here- look at the Auto-temp stuff at the Imperial site to get an idea of what you have.

http://www.imperialclub.com/Repair/Air/index.htm

Rick

__________________
80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

I have the same exact problem with my 80 300SD, I replaced the "voodoo board" but it didnt fix anything so i dont know what to say i think its a vaccume problem

Geez, another case of the folly of making something more complicated than it need be. I'm reminded of the famous case of NASA spending countless dollars and time developing a pen that would write in zero gravity, while, the Russians, used a pencil...

I'm becoming resolved to the notion that my defrost only system may have to suffice. We live in a cool place anyway, and can't imagine using AC but for a few days a year. At least the defrost does blow through the side panel vents. So my feet stay cold a little longer, oh well.

I think I'll troubleshoot all the simple and obvious stuff, and then call the Indy who worked on it last to see if they will check their recent work for free, and then maybe chalk it up to a 30 year old car with a silly system that isn't worth fixing...

Hey "anarchy", did you replace your voodoo board with the $600 unit mentioned here?

__________________
Where there's a will there's a way
1978 300D