|
|
|
|
|
#1
10-21-2009, 02:02 PM
|
|||
|
|||
ccu trouble
I have searched for a similar post, without any luck. I have a 1985 300CD and replaced the ccu unit about 18 months ago. Everything worked fine until recently. Now, if I want a/c I have to turn the temp control wheel all the way up, there is no in between. If I turn it down 1 notch it turns on the heat. Could it be the temp sensor? The tubing is in good shape.
|
|
#2
10-21-2009, 07:11 PM
|
||||
|
||||
|
Was the new ccu new? If not, it may have cold solder issues, quite common.
__________________
83 SD 84 CD
|
|
#3
10-21-2009, 09:30 PM
|
|||
|
|||
|
I don't remember for sure. What can be done with a cold solder issue?
|
|
#4
10-22-2009, 12:59 AM
|
||||
|
||||
|
I had a similar problem on my 300D. The temp dial turned the heat either full on or full off, nothing in between. A relay inside the CCU was also clicking constantly if the temp dial was on heat. I took apart the temp dial and cleaned the potentionmeter with brake clean, reassembled and the clicking stopped and I have temperature control on the heat again.
 Too bad my AC does not work.
__________________
85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked
|
|
#5
10-22-2009, 06:47 AM
|
|||
|
|||
|
thanks I will try that
|
|
#6
10-22-2009, 10:04 AM
|
||||
|
||||
|
also, Go ahead and dissassemble the top portion of the CCU and check for Bare Copper where the green silicon has burned away, potentially causing a connection to be, well, dissconnected. At that point decide whether to resolder or to turn that unit in as a core. Resoldering voids it as an acceptable core.
__________________
 77' 300D, "Cartman" SOLD @ 150K (didn't know what I had) 83' 300SD, "The Superdon" 325k+ @ 28mpg 95 E320 wagon, "Millennium Falcon" 231k+ @ 24 Mpg 95 E300D, "Sherley" 308k @ 33.69 Mpg, currently anticipating a head 99 Suzuki Intruder "Trudy" @ 45 mpg
|
|
#7
10-22-2009, 11:08 AM
|
||||
|
||||
|
I've re-flowed some cold solders, you would see small cracks surrounding the pins.
__________________
83 SD 84 CD
|
|
#8
10-22-2009, 05:34 PM
|
|||
|
|||
|
I've recently had similar gremlins with my CCU. Resoldering the ccu fixed some of the issues, crimping the left and right CCU's connector (female) pins solved a few other problems.
Then I found the AC compressor relay intermittant. Burnished it's contacts and all is well now. I now know more than I ever wanted to about the W123 CCU wiring. 
Last edited by Whiskeydan; 10-22-2009 at 05:56 PM.
|
 |
| Bookmarks |
|
|
Linear Mode
