bodyart27

I also have a ‘84SD, and mine would blow hot air out of the defrosting vents as well as other malfunctions no matter what I did – including replacing the “mono valve”. Finally got fed up and pulled the CCU unit (or whatever its called) and took it apart completely. Found where the sides connect to the base circuit board - all the solder joints were cracked. Got a cheap-o soldering iron from Radio Shack and some silver solder and re-did all-solder joints. Has been working as designed since then (around 6months).

It is quite simple too do if one is somewhat mechanically inclined and remembers where everything goes. Making a schematic of how it comes apart helps a lot in re-assembling.

Thomaspin (member of this forum) has an excellant web site on w-126s - check it out

One thing to consider: Once the unit is taken apart, most rebuilders won’t accept it for a core!

Good Luck

Jim