We have 5 ceiling fans in our house and all 5 are the same brand, but unknown. The fans were in the house when we purchased it. All but one runs perfect, but the one on high is like the others on low. Does anyone have any suggestions?

Does it have a pull cord and a wall speed controller? If so you need to set the pull string to High speed first in order to get the wall controller to match the proper speed. Put the wall controller on MAX, then pull the string until the fan reaches max speed.

It only has the pull cord on the fan, no wall switch.

Hrrm, Try this link. General ceiling fan troubleshooting and help FAQ- Ceiling Fans N More

Sounds like a bad capacitor:

Ceiling fan capactors - troubleshooting and resources - Ceiling Fans N More

Check the troubleshooting link first though