There are a few different things that may be causing the problem.
IOW, There are other components that could cause the motor to fail to run.
The best thing is to look in the yellow pages and call out one of the companies close to you who can diagnose the problem on site.
There's a good chance they will have the parts right on their service truck to fix you right up.
If the unit continues to run when the fan fails to operate, it very possibly could cause more serious damage.
The problem is that when that happens, there are no safeguards to keep this damage from happening.
Running the system without the condenser fan running could cause your compressor to fail.
That would be very expensive.
Call one of the companies to come out and fix it up for you, they'll be able to troubleshoot the probelm and fix you up.
Good luck with it!
The reward for doing a thing well... is to have done it.