I have a new problem on my 525... the climate control blower runs full on all the time, even when I switch the control to OFF?

Anyone know right off if this is the control knob itself, or some other control element (relay?) under the dash?

To worsen the problem, the AC switch will no longer latch ON, for now a well placed toothpick is wedging the thing into the ON postion, but I wonder if I should shop for a control panel....

Thanks