Suburban electrical problem

Is there any fix to a 30amp circuit breaker that works the rear defrost and power locks on a 94 Suburban. The 30 amp circuit breaker is getting very hot and smoked one of them while driving. This happened months ago and I replaced the 30 amp with one that had longer fingers and it worked fine for months. Is there any easy solution to tracing this electrical problem.

Thanks

it should't be on long enuf to smoke the breaker unless the rear defroster isnt shuting itself off, or there is a short. test light on rear defog wires will tell if its running after but as far as the short there is no easy way.

Thanks for the help. I will check to see if the rear defrost is staying on for soime reason, but beleive there is a short somewhere.