My car stinks like fish whenever I turn my heat or ac on.
Any grumpy old men around
Ask you shop to make sure the AC drain port is flowing freely. You may have mold spores growing in the vent system. Shops have chemical treatments which can sometimes help without needing to disassemble the dashboard. If you have a cabin filter good idea to replace that of course.
The heater core may be leaking coolant, does the windshield fog up?
My first thought too. That movies made me homesick for Minnesota.