2001 Windstar- I have no heat or defrost. I do

I had this problem and noticed a faint clunking sound behind the radio. It was the blend door motor that needed to be replaced. The motor has small fine tooth plastic gears that wear out and won't open to allow heat.

To check the thermostat, start the engine and hold your hand on the upper radiator hose. When the engine reaches operating temperature, the thermostat will open fairly suddenly causing the hose to become hot almost immediately. If it gradually becomes warm from the start of the engine, then replace the thermostat. If the hose check is ok, then check the two heater hoses---both should be hot when the engine is warmed up. If ok, then look for air control valves that may have bad vacuum hoses under the dash.

It's not the thermostat.If the engine reaches operating temp.The heat is directed by shutters or gates controlled by either vacuum or cable. Under the dash board on the passenger side is where you may see a vacuum hose attached to a vlve. Remove the hose and feel for vacuum. If a cable, ck that it works the valve with the controls There are several of the valves and each must be checked until you locate the one that blocks off the a/c and directs the air through the heater core. Good Luck_Ned_