Marshall, Thank you taking the time to respond to my post. I did actually include in my two previous posts that I have actually already gone through the diagnostics in the MBZ climate control service manual up to the point where I need a $400 dollar test fixture to check the electrical components of the ACC. I also stated that I did in fact test all of the vacuum pods in the ACC and only one tested bad. The pod the that controls the air to the center vents tested bad. I was also able to determine by running the functionality tests in the ACC manual that the only time I get air out of the footwell vents is when the button with the solid up and down arrows is pressed. The air then consistently comes out of all vents including the footwell vents. This leads me to suspect that the vacuum manifold is not as likely to be the culprit.
Ideally, I would like to run the electrical component test using the nice breakout box/test fixture that Mercedes shows in the ACC manual, but I cannot see spending $400 plus dollars for a very specialized tool. If someone has test fixture they would be willing to loan out, I would be very grateful. My questions are actually based on the test results I obtained, and not intuition. I do actually own American and Japanese vehicles and I try to be methodical about determining the cause of the problems on those vehicles as well. However the need for special tools creates some additional problems when running diagnostics. I was hoping any persons with more experience/knowledge with the early W124's than me might respond. Marshall thanks again for your response. -Steve > > Message: 7 > Date: Thu, 03 Nov 2005 13:32:27 -0500 > From: Marshall Booth <[EMAIL PROTECTED]> > Subject: Re: [MBZ] 1987 300TDT (W124) Climate Control Problems > To: Mercedes mailing list <[EMAIL PROTECTED]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > [EMAIL PROTECTED] wrote: > > Based on on the response that I got to the post below, it seems as though > the cause of the ACC problems may be the control unit. I believe the > control unit is original and has never been changed. Any additional > thoughts or ideas? > > > > After looking around, it seems as though a "rebuilt" control unit is > > available. The ACC control units are rebuilt by Programa. Does anyone > > have any experince with the Programa rebuilt climate control units? I seem > > to recall readig some negative posts about Programa rebuilt climate control > > units for the W123. > > > > Thanks, > > > > -Steve > > > You REALLY do need to run the diagnostics listed in the manual before > condemning the control unit. With many failures the system defaults to > DEFROST mode. Could also be the vacuum manifold or some of the vacuum > actuators (very likely to fail in an '86-'87 126/124 model car) that are > not properly functioning. Read the manual to determine HOW the system > works and perform the diagnostics to find out which parts are not > operating as they were intended to operate. Throwing parts at the > climate control system of a Mercedes is usually the most expensive way > to solve the problem - and it actually may NOT solve the problem. The > system is VERY complex and it does NOT operate in a manner that is > intuitive to most people (especially people that have a background > working on American or Japanese cars). > > Marshall > -- > Marshall Booth Ph.D. > Ass't Prof. (ret.) > Univ of Pittsburgh School of Medicine > Department of Pharmacology 1300 BST> Pittsburgh PA 15261 USA > [EMAIL PROTECTED]> > > >
