Bad heater motor bearings? 67 Dart non A/C
That sounds exactly like something got in the way of the blower (squirrel cage)
When you put your lever to the far left it closes the door inside the heater and the fan spins faster due to not being able to pull air.
This is probably why it goes crazy when the lever is in the far left position.
Those non AC boxes are easy to get out, you just have to deal with the J hook inside the right vent box.
Then it's just the three bolts around the blower motor under the hood, the hoses and cables.
Cables are best gotten to with the glove box out.
Then pop the clips off that hold the case halves together and clean it out.
I used contact glue (3M weather strip cement) and replaced all the vent and control doors foam.
That sounds exactly like something got in the way of the blower (squirrel cage)
When you put your lever to the far left it closes the door inside the heater and the fan spins faster due to not being able to pull air.
This is probably why it goes crazy when the lever is in the far left position.
Those non AC boxes are easy to get out, you just have to deal with the J hook inside the right vent box.
Then it's just the three bolts around the blower motor under the hood, the hoses and cables.
Cables are best gotten to with the glove box out.
Then pop the clips off that hold the case halves together and clean it out.
I used contact glue (3M weather strip cement) and replaced all the vent and control doors foam.
