Hello - I just bought my first Benz. Its an 1987 300SDL, I love the way it rides but the climate control has a mond of its own. If I turn it off....it will turn on and off on its own, but as soon as i press the O button it turns off. I hear a clicking from the black box behind the control unit (consol is pulled out) I see and arm moving back and forth. Not sure if this is athe culprit or if its the CCU itsself.

Any help would be great.

Thx

Late (91) SDL CCU on eBay (mine):
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=010&sspagename=STRK%3AMESE%3AIT&viewitem=&item=200261695278&rd=1

__________________

Gone to the dark side

- Jeff

The CCU in most vehicles of this age is usually toast. You can try and solder the boards internally with varying results. Or, you can get a used one on e-bay with varying durability.

A proper rebuilt is a bit above $200. and has a 3 year warranty.

The vehicle will also likely suffer from leaky vacuum pods that operate the vacuum doors. The failure mode is defrost all the time.........the vacuum is leaking from one of the other pods and the system won't operate the doors.

If you are a hands on person the soldering repair to the ccu is definetly worth a try..on my 87 300d the control is different from the How-To for older model Mbs i located through this site, but is basically the same it just does not have the side boards due to the plugs are on top, which i felt actualy makes it easier due to the bottom cover is the only part that has to come off of ccu, all you need is a fine point soldering pencil, rosin core solder, a magnifying glass, a bright light and a steady hand to locate and repair the cracked cold solder joints on the bottom of the board, i dont have any pictures but i found them on this site by searching for a while but the joints you want to fix are the round surface joints (mine had many cracked joints..i did this repair on my car bout a month ago now electrically it is functional in every way temp wheel, all buttons and especially off is now OFF.., but as stated by others my vacuum pods are gone except the floor vent pods they do function when turned to heat otherwise always defrost and outer vents...

P.S If you have the pod problems and want the center vents to work you can remove the center vent from dash and wedge the vacuum vent door open to center vents behind manual door then put back together and no one will know but you.., i did this because i live in las vegas and A/C is a necessity..

hope this all makes sense,
ARLO

Thanks guys - I did the resolder - not worth my time. Not sure If i'll gamble on a used one OR shell for a new one. ITs in defrost all the time too now that I checked. Whats the deal on replacing the vac pods? Where and how much? I'm in canada so for the winter I need defrost and floor heat, if I can get those to to stay on all the time I'd be set.

I'm doing the monovalve replacement this weekend as well.