Problem:
No floor vent function.

So far:
Pulled the red/yellow line from the pod, pulled vacuum and saw that the flaps functioned. Tried to pull vacuum on the red/yellow line - would not hold at all. Pulled the swithover valve from behind the CCU control and tested for vacuum: vacuum holds nicely on the top (verticle) port - no vacuum whatever on the side (horizontal) port.

My conclusion:
Bad swithover valve.

Yes? No? Maybe!

__________________
Dale

oh yeah! The picture...

Attached Thumbnails

 

__________________
Dale

Check your vacuum coming into the cabin. If it is less than 15", your vents won't work properly. My line was green and yellow, if I recall.

You also need to check the signal at the switch. Hook up a test meter to the contacts on the plug, push your center three buttons with the system on, and see whether you have 12v.

ALternately, you could test the vacuum being pulled at that switch when the system is on and you push the center three buttons. If you get a vacuum, your switch is fine. If not, you either have no signal coming from the control unit, or bad vacuum somewhere else.

IF you have good vacuum coming into the switch, AND if you have 12v at the plug, the switch is bad.

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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

Thanks, Peter. I'll test the signal at the switch contacts as well. (Those switches are very 'tight' in there, not much room to work, but I'll need to reinstall it to test... !)

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Dale

It is tight, on mine as well (85 300 wagon). I took out all the panel switches (including the top set) and radio completely, had enough slack in the wiring to plug up the control unit.

It was a pain, but I had the same problem you do for a whole winter, and it is nice to have heat on my feet again.

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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

I have also taken out the upper set of switches but haven't removed the radio yet. (Now would definately be the time to R&R the radio as I have a nice ALPINE CD/MP3 head unit from another vehicle I sold recently!)

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Dale

Well, I reinstalled the valve and tested for vac with the system ON and the three middle buttons pushed. Result - no vacuum.

Tested contacts and found >12V.

Bad. Ba-a-a-d valve!

Phil, oh Phil-l-l-l!

__________________
Dale

Did you check your vacuum coming into the cabin? is it steady when you give it some pedal?

Don't buy a switch until you read your vacuum coming into the cabin. Trust me.

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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

Woooo-hoooo!!! I now have legroom heat!!!

Legroom vents are now operating after installing a new vac switchover valve behind the ACC pushbutton unit. It was valve #2 of the series of valves in there. The vac line is red/yellow stripe.

Job wasn't too bad...the magnetic tip screwdriver was a must have for this one as it is impossible for me to get a hand/fingers in there!

Anyway I just thought I would 'close the loop' on this thread and report the results.

__________________
Dale