I just installed a new ceiling fan in a room where the switch previously controlled only an outlet and there was no power directly at the switch, only at the outlet.
At the switch box I wired the two white wires together and then wired the black wires, one each, to the screws on the switch.
The switch works but the lamp and ceiling fan light come on very dim only.
What did I do wrong and how can I fix it?

Did you re-connect the white in the outlet? There is one that is connected to the hot that needs to be re-connected to the neutral. Sounds like what you have is the outlet in series with the fan/light.