heating / cooling - PeachParts Mercedes-Benz Forum

Benz300 · #1 11-03-2003, 01:10 PM

my 260E developed a new problem.
I had the heater turned on the other day and then afterwards wanted to turn on the cold fresh air again. but the air was luke warm even when I had the climate control all the way towards the cold settings. the center vent never opened up either.
I took it to the dealer and they're saying that It is because of the leaking vacuum lines behind the dash. and giving me a rough estimate of 9 hours of labor and parts on top of it.
Does vacuum lines leaking cause the inability to change the warm air/ cold air function ? I always thought it was the climate control unit. what does the climate control unit in turn change so that we get the warm or the cold air ?
thanks for the help..

haasman · #2 11-03-2003, 01:37 PM

My guess is that it isn't the lines, they are pretty hard and durable, but more than likely are the parts they attach to, such as the vacuum control modules.

These do wear out. Depending on how exten$ive the process, it is always a good idea to replace all of them where you are there.

I just had to do a dashadectomy on the 190e and I definitely replaced all the vac mods.

Haasman

Benz300 · #3 11-05-2003, 11:07 AM

could a faulty climate control unit, i.e. the temp control wheel cause this to happen ?
I'd rather replace the easy part first before giong with one of the most expensive repairs !.

haasman · #4 11-05-2003, 12:00 PM

Benz300

I respect you for asking that question and to be hesitant to pull the dash for the obviou$ reasons.

It sounds like it isn't your temp controller because it did adjust the temp. It sounds like a vacuum controller to me because it didn't bring the air out of the center vent, which is controlled via a vacuum actuator. Since your 260E is of the same vintage as the 190e I just did (16 +/-) years old, I would have to guess again that it is the vac mods.

If you want to be conservative and approach the problem very systematically, there are step-by-step flow charts to determine and verify what components are failing, I believe found in the 124 repair CD.

It occurs to me that since all the vacuum lines for this system terminate under the dash on the right side, that one could drop the lower section, find the vacuum control block, find each line that goes to each specfic vac mod and test it for leakage.

Some of the vac mods are single connections (one function) while others have two vacuum connections supplying a regulating feature. My point here is one side could be good while the other has a tear and creates a vacuum to leak (doesn't work). The lines are specific and can be traced.

In a nutshell: If it is determined that you do have leaking vacuum modulator(s), you will have to dig into the dash. Some are much more accessible, the center console area, while others are much more time consuming and require removing a lot of parts. If you are a DIYer it isn't really that bad.

To make you feel better, at least your heater core isn't leaking ....

Hope this helps,

Haasman

Benz300 · #5 11-05-2003, 05:32 PM

Thanks Hassman,
I'll look into that in more detail. You did however bring another topic which is of interest. I've read posts on how the heater core at one point or the other fails and requires the whole dash to be pulled apart.
My question, should I 'dare' to replace the heater core while the dash is apart ? how many more hours' worth of DIY would that consist of ? And since the dash will be apart, are there any other components that are advisable to be replaced while I'm at it ?
thanks again..

haasman · #6 11-05-2003, 05:40 PM

Regarding the heater core .... it would be a bummer to have to go back into the dash to do it later. More parts would only include the heater core, O-rings which should come with the core.

Labor .... well it does take more effort since the heater core is inside of the control unit box (for lack of better description). How many more hours I am uncertain as to the amount. My guess that it would add maybe another 3 hours +/- . . ....

The nice thing about doing it all at once is you know (peace of mind) that all those buried parts are taken care of, sans the heater motor and evaporator core that are accessed anyway from the otherside of the firewall.

Are you planning to make it a DIY'er?

Keep us posted,

Haasman

Benz300 · #7 11-05-2003, 06:37 PM

I suppose I'll "dare" to start this as a DIY. when I do, I'll take pics. as to when I'll start this depends upon the weather. but I'll keep everyone posted.
thanks again Haasman ! You're always really hepful.