High Speed Blower

We have two squirrel cage fan with a toggle switch with off, low and high speeds. High and low speed used to be materially different. Now they are the same. We just replaced the switch. You can hear a little difference now, but at the top, he turns and runs 2-3 seconds and turns off. The bottom, it will happen more as it should. Ideas?

Sounds like a bad engine for me.

You can see if the squirrel cage needs cleaning and if there is a place to apply the engine oil.