Thanks Diseasel300!
Kind of a long story. Last winter, heat failed. I had a break in the weather, so I installed a MTC monovavle repair kit. You are correct, the MTC is junk. Still without heat, and another project tying up my shed (workspace), I was forced to bring the car to an indy repair place. The indy changed out the monovalve repair kit, with a new MB, and also told me that the magnet, that actuates the plunger was bad, so he replaced that with a known good (allegedly) used one. Heat worked OK for a while, but soon was not working, more than working. Occasionally, it would work, as if it was dependent on what button I had engaged on the push button unit. In the cases where it did work, it would decide to quite supplying heat after a few minutes, and I was unable to regulate temperature. AT one point I tried disconnecting the monovalve wires, but that was no help either. I wanted to rule out the Aux Pump. Also wondering if it might be a temp sensor either cabin or ambient air temp. AC and vents all working as they should.
Thanks for your help!