[BOOZER]

Before you go ripping into the dash, do a quick underhood check. With the vehicle up to operating temp, check both heater hoses at the core. If there both hot you know you have flow through the core, not, then more than likely a pluged core.
With it cooled down check the coolant, look like mud? Hope not. If yes do a search to see how to flush.
The tempature door actuator is located on the top of the HVAC module, to the RH side, behind the glove box. It will be a small black box about 4"X4",
with a single connector w/5-6 wires. Good Luck.