Thanks for the advice! It'll be a few days before I can do the flush. Update to follow! Also glad to have found this forum!

Based on both of your replies and my suspicions, looking like cooling system flush I did with only distilled water was not adequate. Can either of you recommend a good flush product?

Original Owner: 2003 Cargo 129,800 Miles; Van Location: South Florida First ever coolant flush 4/2018 at 101,798 Miles. Original and current coolant is Dexcool. Note: Water temp normal both before and after flush. Historic coolant temperature (depending on outdoor temp) has been 195 to 210 degrees. ...

Nope! No rear heater. Thanks!

Wiper pump is working. Wire colors for the 'mystery connector' are black and the other wire is black & grey.

PS: Thanks for shifting my question to proper category.

I recently replaced the serpentine belt, tensioner, idler pulley, thermostat and back flushed the radiator and heater core. Afterwards, in the vicinity of the AC evaporator, I discovered a disconnected wire that is approximately 10" in length. I've not been able to locate a connection within it...