Touchy temperature control

My '98 Venture has always had a touchy temperature control. It goes from hot to cold in just one click of the knob. With it in the exact middle you can move it one click left and you freeze, one click right and you bake. I'm assuming it currently has no real variable control. It's either hot or cold. Once fully warmed you have to move it back and forth constantly to control the temperature. Any help is appreciated.

I would look for possibly a sticking air blend door.

I would look for possibly a sticking air blend door.

Is there a quick and easy way to the air blend door? I've taken several vehicles heating systems apart in the past. Some were easy, some were a big pain in the you know what.

Is there a quick and easy way to the air blend door? I've taken several vehicles heating systems apart in the past. Some were easy, some were a big pain in the you know what.
First step is to take the driver side insulator panel off (at the bottom of the dash near the driver's feet.)

Then get a good flashlight and watch what happens to the control levers when you move the temperature knob around.

Good Luck & Take Care,