Cadillac Repair: HEAT, buick park avenue, heater hoses

Question
1999 Buick Park Avenue Ultra. I know your a Cadillac expert but was hoping this was close as there is no Buick experts around. It involves the heater being dead. I recently had the thermostat replaced as it overheated. All was well until yesterday the defroster did not work until the thermostat opened. The AUTO setting worked fine. The temp of the 3.8L was 180 - 190 degrees. Today the defroster did not work at all as well as the whole heater system on AUTO or any other setting. Temp of the motor 190-210 degrees. Thought I would ask before replacing heater valve, heater core or vacuum lines.

Answer
What EXACTLY is wrong with the heater system ?.

Does the blower motor work ?.

Are the heater hoses on BOTH sides of the heater valve feel about the same temp ?.

Remove the vacuum line going to the heater valve and see if you get heat.

Are you getting water flow thru the heater core ?.