monovalve kit question

[dubadxx]

I have purchased the monovalve repair kit, for an '84 300D, made by MTC. I am still having the no heat at speed issues. I noticed when installing the new part that it doesn't move freely in the body of the valve. The one I replaced moved up and down in the sleeve easily. I have inspected the new one for rips and tears and it appears to be in good shape. I'm getting ready to pull the ACC and do the solder repairs anyway, as there are glitches in the pushbuttons, for example, need to start with defrost before the econ turns on. And the defrost default is not always heat when initially turned on. And the strangest glitch is when the overhead light just comes on by itself occasionally when the ACC is on.

[BWhitmore]

Quite often the mono valve diaphragm is bad but just as often the mono valve magnet is no good. If you can get a used mono valve that is worth a try. It worked on my 1985 300D.

[eatont9999]

Originally Posted by dubadxx

I have purchased the monovalve repair kit, for an '84 300D, made by MTC. I am still having the no heat at speed issues. I noticed when installing the new part that it doesn't move freely in the body of the valve. The one I replaced moved up and down in the sleeve easily. I have inspected the new one for rips and tears and it appears to be in good shape. I'm getting ready to pull the ACC and do the solder repairs anyway, as there are glitches in the pushbuttons, for example, need to start with defrost before the econ turns on. And the defrost default is not always heat when initially turned on. And the strangest glitch is when the overhead light just comes on by itself occasionally when the ACC is on.

I installed one made by MTC yesterday morning. It has been working wonderfully so far. Made in India.

[my123ca]

Originally Posted by dubadxx

for example, need to start with defrost before the econ turns on.

Thats a symptom of a bad blower or is about to go bad.

[mistersooty]

I had many issues with the acc in my 300 sd. In regards to the blower it was suggested to replace the blower motor bushings. I was able to pick up some bushes at my local ace/true value and file them down to size. I also did the re-soldering trick, replaced the foam tubing that was falling apart between the temp sensor in the dash and the blower motor, and replaced the mono valve insert.

Ten plus year later still no problems. It was very frustrating at the time as the failures in the system had no rhyme or reason.