Electric fans help, one not working

[chixwithtrix]

Just bought a used set of flex-a-lite radiator fans and the passenger side fan is stalled somehow. Here is what is happening:

Wired both fans into one main wire (14 gauge) and went to a switch so the it would turn on both fans at once.
Connected the wire to battery power and only the drivers side fan would barely spin and move very little air. The wire would also get warm.
Disconnected the passenger side fan and only wired in the drivers side fan. Connected the power and the d-side fan came on at full power.

What would cause the p-side fan to not work and how would I go about fixing it