I'm having some issues (been gradually getting worse for several years) with my 85 300td climate control. Sometimes, the system just won't turn on (no blower). I press all the different buttons and nothing will happen, SOMETIMES it will switch on when pressing buttons (not consistent what button is successful in activating it). Once the system turns on I can switch the settings and it usually works fine. I recently replaced the blower motor so I don't think thats the issue, so I figure its in the CCU control unit. Coming into winter, its important to me that I'm able to heat (and especially defrost). Is there way to manually control the system (my car is kinda a "junker" and I don't want to invest much time or $$ fixing the problem properly and I'm not afraid to mount some radio shack switches etc). Can I use a switch to manually control the monovalve and blower motor? If I could just keep the system stuck on High Heat and Defrost and then operate the fan manually with a switch that would work for this winter..... Thanks in advance for your help

__________________
'85 300td Frybrid WVO Kit

Sounds like you just need to resolder your ccu. Might be easier than reengineering it.

First, if you want to get your system working, I strongly suspect your pushbutton unit (ccu) is gone, like the other response suggests.

If you are handy with a soldering gun there is a DIY on here that shows a rebuild.

Second, if you are sold on de-engineering, Google is your friend. I have seen either a website, or possibly a thread here, where a guy did about what you are proposing.

If you replace the monovalve with a fitting you will have heat flow all the time. You could probably plumb in a manual heater valve from another car to achieve control. How you translate that into remote control from the cabin would be a challenge.

It wouldn't be that hard to run power to the blower.

HOWEVER, I actually had a Volvo 760 Turbo wagon (read: old Peugeot auto climate control system) winter beater years ago, where someone had done just what you propose to bypass the dead system. I would only live with an arrangement like that as a last resort, again.

__________________


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

Another possibility would be to cruise the used parts forum here for a used climate control switch panel. You could try Yotadiesel, who is moving parts from a 300d now....

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/325271-1985-300td-part-out.html

__________________


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