Volvo: 1995 volvo 850 wagon, volvo 850 wagon, volvo 850

Question
when i turn the heater on anywhere from turning the knob to 1 through 3 it squeals. When it's on high # 4 no noise. any solutions to check to fix the problem.  

Answer
It sounds like the bearings are starting to go on your blower motor.  If thats the case, you'll have to replace it.  Another possibility is that something might be caught in the vent ducks under the dash.  If that's the case, a shot of compressed air might dislodge whatever might be stuck.  However, if the motor is going bad, you'll have to have it replaced.