My garage has a studio with electric baseboard heat in one room and an
electric wall heater in the entryway. It's expensive to run - something like
22 kW - so I mainly use that room in warm weather.

The entryway thermostat is an "Electromode Model M7-D double line break"
with a huge bimetallic strip. At random intervals, a kind of
screeching/hissing sound comes from it. (At least, I think that's where it
comes from. It never happens when I'm right near it.) I pulled the double
breaker than powers the baseboards, and turned the thermostat built into the
wall heater all the way down. So there shouldn't be any current flowing,
right? So where does the noise come from, and can I do anything about it w/o
cutting wires?

Thanks!

Theo