I just installed a replacement 52 inch Harbor Breezefan and I am experiencing the same problem as the last one. It appears to turn only at medium speed when on high. I have four other fans of the same type and all spin considerably faster. My son said the original turned as fast as the others and a couple of weeks ago the symptoms appeared. I changed the wall switch and nothing has changed.

What type of wall switch do you have?

The switch is a simple toggle switch 110v.

It sounds like a bad capacitor, but that would explain why two fans in the same location exibited the same problem. Do you have a voltmeter?

Voltage at switch and fan is 123.5. I now notice that even the light seems dimmer than the two adjacent rooms

123 is good. Something may be wrong with the fan. Is it a remote fan?