[andya]

I've found that one of the two switchover/changeover valves for the heating has a leak so I need a new one.

The EPC shows two part numbers, implying that the two valves are different, however I thought they were the same?

A0008000273, A0008000373

It seems these parts are no longer available and were replaced with yellow and green colored versions A0008000573 (yellow) and A0008000673 (green). Looking at pictures on ebay they appear to be completely different to what I have.

So maybe I am looking at the wrong image in the EPC?

Thanks, Andy

 

[andya]

I tried bench testing both valves. When applying 12V there is no current draw, no sounds and no change in the routing of the vaccum (still goes from U to F ports). So maybe they are both broken?

Andy

 

[cushjbc]

Andy,

I think you have the correct EPC diagram. Do you have service manual article 83-020? It shows how they are wired and it looks like the pins on those switchover valves are polarity dependent. The two diagrams also show what power interruption (heat levers down - microswitches open) does to those valves and what power application (heat levers up - microswitches closed) does. From memory, there is a locator on the electrical receiver that insures 12V goes to the correct pin.

If you have that bench test set up correctly and can't get the solenoid to switch ports, I think you may have to replace them. I pulled some salvage ones and will dig them out when I get home. Functionally, I can't see the difference in those valves; no idea why 2 part numbers.

 

[cushjbc]

Andy,

This item from eBay is cheap, from a reputable vendor. The picture has the yellow and green items I think you found and 2 types of Pierburg switchover valves that our cars use. The one with the white cap I believe could be used on the left side (closest to the heater vacuum element). Maybe that white cap is just a filter for ambient air venting.

79 Mercedes R107 450SL Climate Control Valve Assembly

 

[andya]

Do you have service manual article 83-020? It shows how they are wired and it looks like the pins on those switchover valves are polarity dependent.

The male and female connectors do not have a tab or notch to ensure polarity. I didn't notice any markings but I didn't check that well. A quick Google search seems to indicate that polarity is not important for solenoid valves. Not sure if that is really true or not.

Andy

 

[andya]

Andy,

This item from eBay is cheap, from a reputable vendor. The picture has the yellow and green items I think you found and 2 types of Pierburg switchover valves that our cars use. The one with the white cap I believe could be used on the left side (closest to the heater vacuum element). Maybe that white cap is just a filter for ambient air venting.

79 Mercedes R107 450SL Climate Control Valve Assembly

Thanks!! I have bought it. Andy