Chevrolet Repair: 1990 G20 van heater blower, chevy g20, conversion van

Question
My vehicle is a 1990 Chevy G20 conversion van.  A couple of years ago it developed a problem with the heater blower intermittently cutting out. I have had it in four different shops since then. The blower motor has been replaced, as well as the resistor, the relay and a circuit module.  After all that, the best result I've had is that the fan would run only in the MAX position.

A couple of days ago this changed.  Now the fan will not shut off in any switch position.  It even stays running when the engine is shut off.  I have had to disconnect the ground wire from the blower motor to make it stop.

Answer
HI JOHN,THIS COULD BE CAUSED BY A FEW THINGS,BAD OR STICKY RELAY OR BAD SWITCH..THE SWITCH MAYBE SHORTED CAUSING POWER TO STAY ON ALWAYS....CK OR SWITCH THE RELAY AROUND WITH ANOTHER RELAY OF SAME STYLE,SEE IF THIS WORKS.IF NOT SWITCH IS BAD OR HARNESS HAS MELTED CAUSING IT TO POWER UP...CK THE ABOVE OUT AND GET BACK TO ME..GOOD LUCK,,TOM..