Whistle at blower motor

[brewyourown]

Within the past 2 months, the blower to my furnace has developed a whistle. It's not terrible yet, but appears to be getting worse. I have changed filters, etc...I have listened with my ear, the whistle is primarily generated inside the furnace itself by the blower. It seems to get worse once the burner turns off and it's in the final 2 minutes of a cycle.

any thoughts? Dust inside? Is there regular maintanance to the blower motor necessary? The plate on the outside says no lubrication is necessary. I have a 3 year old Carrier Oil fired Hot Air furnace.

[t527ed]

a whistle is usually a sign of air sucking in. could be door not on right and undersized return. could also be bearings in motor. call for service and let a trained ear hear it.

[mjk_na]

My car air conditioner is giving the similar (I guess) whistle sound, especially when I speed up. It makes the "wheee" sound. Quite scary especially when you're driving alone at night

There is either a leakage at the intake duct, or intake duct being undersized as t527ed mentioned.

If the problem emerged just recently, undersized return or intake might not be an issue. Non-functioning dampers might be an issue.

You might need a contractor for major rectification job.

[blove tech]

Air is being sucked in somewhere causing the whistle. Probably around the return drop, usually at the corners. try sealing the corners or anywhere you can see a visable crack in the metal, use silicone to seal it up. Make sure door to filter rack is closed tightly.