It's more likely you bumped a vacuum line while working on the car, like I do all the time. Take a good look around for disconnected lines.

What does your voltmeter say when you hook it up to the mono valve connector?

I haven't had a chance to check the mono valve with a voltmeter.

However the plot thickens.......Just noticed that regardless of the setting that I have my climate control unit set to it always blows air from the defrost and the two side vents, but doesn't blow from the middle two vents.

Ok another update.....I removed the glove box and found that the temp sensor foam tube had totally deteriorated away. I am going to replace it and see what this does.

Ok I went down to Home Depot and got some 1/2 copper foam tubing and replaced mine. I can feel alot of air rushing through it now which is good however I still get full heat. So at this point I theorize that I have a bad temp sensor. I will have to check it with a voltmeter when I get home today.

see post #9

you can replace it with normal pipe insulation. it connects the cabin temp sensor on the top of the dash to the CC system. on heat it shuts off the monovalve when the cabin reaches the dialed in temp on the CC unit temp wheel (or so in theory).

on the other hand you should be able to shut off the heat with the temp wheel by setting past the click stop on full cold. did you try that? that is supposed to override the CC temp sensing function.

what we're doing here is trying to eliminate all possibilities before having to say replace the CC control unit in the middle of the dash....

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

also make sure that fuse #14 is still holding....

you should be able to make the monovalve 'work' by unplugging it's plug and jumping it with 2 wires .. one from the positive post of the battery and the other to any ground.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

Fuse 14 is still holding. I did the mono valve check as you described and I can feel the mono valve working.

I moved the temp dial but there is no change through the entire range of the dial. I am going to take out that push button unit and check all the solders and the circuit board.

Ok I don't have the most experience with a voltmeter so I used the 2000m Vac setting on the voltmeter. I then touched the contacts on top of the mono valve and it read zero. I reversed my leads and still got a reading of zero. Next I took the positive (red) lead from the voltmeter and touched the black/red stripe wire and then took the ground lead (black) from the voltmeter and grounded it to another part of the car and got a reading of 14. I then touched the positive (red) lead to the brown/white stripe wire and then took the ground lead (black) from the voltmeter and grounded it to the car and also got a 14.

So does this mean anything to anyone? Any help would be greatly appreciated. Also on top of the mono valve should the brown/white stripe wire or the black/red stripe wire be the one towards the front of the car? Does it matter? Just wanting to make sure that I hooked the wires up correctly back to the mono valve.

Thanks

I think I have a plan to fix this. I will just install a two way switch on my dash and run one wire wire to the mono valve that is only hot when the key is turned on like the radio and then run another wire for ground. Just flip the switch to fully close the mono valve and flip it off to fully open it. This will work cause I don't really ever use anything but full heat or full cool.

I've always wondered how that kickdown does anything since there aren't any electrical controls on the transmission. Any idea?


Also, the horn is on fuse #14. An intermittently shorted horn wire inside the steering column can blow that fuse.

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Never a dull moment at Berry Hill Farm.

Well I got the fuse problem fixed. It turned out it was the black wire that runs down the side of the transmission was rubbing the transmission and it wore through the plastic wire coating. So I taped that wore out spot up.

I guess this is just a secondary problem that has developed in the meantime. Because just a couple of weeks ago before figuring out where the wire short was I could still put in a brand new fuse and my mono valve would close just fine. Now that I actually have fixed it the shorted wire and am no longer burning up the fuse you would think it would be fixed but like I said I guess another issue in the climate control system has developed.

Bump,

I'm having the same issue. I haven't done anything to fix it yet (haven't had time).

just a shot in the dark but..
if you unplug the aux water pump what happens then?

also do your reverse lights work?

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

I got tired of troubleshooting so I just went ahead and hooked up the toggle switch so now I can just flip the switch to turn the mono valve on and off. Yeah not the best solution in the world but hey at least I am not burning up anymore.