OK, so we just this morning got the last of the four pods in the car (after I've been driving the grandparents Grand Marquis for two full weeks because our explorer's transmission died the day after we took the mercedes off the line )

3/4 of them work flawlessly.

The "defrost" pod does not respond to efforts to make it activate.

It does, however, work perfectly when we manually operate it with the MityVac on the line going into the little junction block thingie.

How do we diagnose whether the problem is a nonfunctional part of the 7-hole vacuum block or if it's a problem in the electronic pushbutton box for the climate system?

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

Anybody?

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

The problem is either the switchover valve for the defrost pod or the CCU.

See if you can verify if a 12V signal is coming from the CCU to the switchover valve when defrost is selected.

I don't think you've got a complete set of data, because the defrost pod defaults to an open configuration. Without vacuum, you get full defrost. So, without defrost, the CCU must signal the switchover valve to open and provide vacuum to the pod.


Also, the defrost pod is a dual pod and is run from two different switchover valves. Have you verified that both ends of the pod hold vacuum? Any leak in either circuit will cause problems.

Which circuits are you testing for defrost?

It is a perfectly good, brand new pod, we checked it before we put it in.

The defrost is still staying on in the default position, that is the problem I was trying to describe

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

The defrost is designed to stay on in the default position (no electrical power to any of the vacuum switchover valves).

Hook up a vacuum gauge to each defrost pod vacuum line. It might help you narrow the problem.

Is it possible you reversed the vacuum lines into the defrost pod?

Sixto
87 300D

I'll get back once I'm more sure what we're talking about, my dad's doing some more checking after work today. (I'm at work now, in the Mercury, so can't check at the moment)

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL