88 560 SL AC problem help!!!
 

I am new to the Forum but I have been enjoying it since. I have a 76 450Sl. Recently I just bought a 88 560SL with the auto climate control which I have not worked in it beofre.

I noticed that AC works fine but all cool air goes to defroster vent not to center vent. I guess I have a bad defroster actuator. I have a question on whether I should replace it with an new one or replace the diaphram on it and where I can get a repair kit for those actuators?

Thanks a lot:cool:

No air to the center vent is a common issue on these cars. I understand that the center actuators are hard to get to without removing a bunch of dash. Check out this link, it might be of help:
http://users.adelphia.net/~rmsmithco/vacuum1.htm

Does full air always come out of the defroster duct, no matter what the climate control is set too? Then yes, I would bet the diaphragm is bad. It defaults to wide open. Luckily it is replaceable without removing the whole dash (though the factory manual says to do so). If you take out the instrument cluster, you can see it on the right side, a colorful plastic pod. At this point, you can hook up a hand vacuum pump to check it's operation. There are actually two ports on the pod as it actually can move the vent fully closed or just partially. Both should hold vacuum and move the lever.

If it turns out to be bad, as far as I know, you need to buy the whole pod, which will run around $50. It is available from the Mercedes dealer or other aftermarket sources, such as this site. To remove it, you will need to grind off the rivet between the pod and lever, such as with a Dremel, and find a bolt or rivet for installation. You may also want to get some new locks and rubber washers that hold the pod to the bracket as you will likely loose them when you pry them off.

I see that the link the previous poster listed has a vacuum diagram. If you have a hand vacuum pump, you can check all the diaphragms for leakage if you remove the glove box cardboard, lower the under dash panel, and shove the air duct out of the way. The Y34 valve unit it back in there and you can disconnect each hose and apply vacuum to each to check for leakage. If you find a leak, you can work you way down the proper line to find the problem.

Thanks a bunch!

Still anybody knows where I can get the diaphragm for actuator thta I can repair it instead of replacing a whole thing?

I don't think the inserts are available for vacuum actuators after approx. 1978. I know the earlier ones (looks like two pods side-by-side) do.

They are available, I dont know where but in my opinion this is essentially 3 actuators for ~$150.00 in a $1000.00 location. I would buy new genuine MB actuators. Save the aftermarket crap or repair kits for the 4 vent actuators which are easy to get to.

I have done this on 2 cars already. Search for a post "Will Sadie ever run again" and just do another search on "center vent"

John Roncallo

Thanks!
 

John,

I think you arre right after giving a second thought. I will go ahead to replace those with OEM actuators and save the headache I may need to go back there again.

:)

I bought my replacement diaphragms from George Murphy, Oak Ridge, TN and they have lasted fine. Hope this helps you.

George Murphy

Performance Analysis Co.
969 Oak Ridge Turnpike, Suite 258
Oak Ridge, TN 37830

865-482-9175 9 am to 5 pm ET M-F
FAX 865-482-9175