I have a 2003 Forester with about 37,000 miles on it and it has been trouble
free. I live in the Cleveland, OH area and our weather here lately has
produced temperatures between +2 to +15 degrees Fahrenheit from daylight to
sunset..

After returning to my garage after driving an hour or so in these
temperatures, I shut off the engine and hear a very high pitch noise coming
from the engine compartment. It seems to be the loudest near the front of
the radiator . It will last for 1-2 hours.

I had my car in for an oil change at the Subaru dealer last week and of
course it didn't make the noise and they had no idea what it could be.

I could not determine whether this noise was produced from high pressure
leak in the AC/heater system or electronic. It seemed to be electronic from
my experience. When I returned home today, it was doing it again. I decided
to lift one of the battery cables and the noise stopped immediately. I then
tried pulling each of the many fuses one at a time, but none of them
affected it.

Has anyone experienced this or have any ideas what might be causing it? I
don't recall it happening last winter with similar weather.