Okay, I've followed several threads on this issue and just want to make sure I'm headed in the right direction before I start screwing something up. Although somewhat capable, I am not a mechanical genius. I have a 1985 300D Turbodiesel (W123). The weather has really turned cold the last few days and I have needed heat. The blower blows fine on all speeds. The pushbutton unit seems to direct air to the appropriate vents. I say "seems" because I get air on the windshield on the defrost setting and air from the center dash vents when I turn the A/C on. I notice little to no air from the floor vents on any setting. Although troublesome, this is the least of my worries. It is darn cold driving this car with temps in the teens and twenties! Heat from any vent would be most welcome!
Based on something I read in another thread, I removed the electrical wire from the top of what I assume is the monovalve on the firewall just inboard from the battery. I say "assume" because it appears to be in the general location described in other threads, it does have heater/cooloant hoses going in and out and disconnecting the electrical connection on top didn't seem to adversely affect any other function of the vehicle. If I read the other threads correctly, disconnecting this electrical connection should result in full, continuous heat as I gather this forces the valve to remain in constnat heat mode. My result - no change in function. I still get full blower action but no heat. I did leave the car run for 10-15 minutes and then drove it for about 10 miles. The engine temperature gauge moves (slightly in this cold weather), but still no discernable heat from any of the vents.
It sounds like a monovalve issue, if my research is accurate. I just want to see if I am headed in the right direction. If so, it sounds like the rebuild kit may be relatively inexpensive ($40?). In the alternative, anybody have any idea what a new monovalve assembly for this model should run? Does it sound like something else might be the issue? Thanks in advance for any advice/encouragement.