Volvo Repair: Volvo, pitch changes, wheel bearing

Question
Regarding a volvo 1990. A friend gave us this car. We replaced the blower motor for the air because of the high pitched squeal it was making. Seems to take care of that.

Now the car is making a high pitched sound once you hit 25 miles an hour. Sounds like the turbines of an air plane in the manner that it begins and ends. Any clue of what this might be? Thanks for any suggestions.

Answer
Nancy,
Can you be a bit more specific? It could be many things, from your description. is it related to engine speed? When you hear it, push you trans to neutral and let engine speed die down while the car is coasting- does this eliminate the noise? Also, while coasting in neutral, speed the engine up to see if the pitch changes. Is it loud? If not, it could be the brake wear indicators. Is it an exhaust leak? Try weaving back and forth a little when you hear it- if the pitch changes, it could be a wheel bearing going bad. Is it related to the blower speed for the heater? If related to engine speed, it could be an alternator bearing, or a baring on a tensioner or idler for the serpentine belt or timing belt. In other words, it could be a lot of things. Any additional clues might be helpful.