rear heater/ac blower

I recently bought a 1999 sport with 103000 mi. The rear heater blower didn't work so I removed the panel and found it to be un-plugged. After plugging it in it worked fine, but the horn didn't sound and the interior lights stayed on when locking the car. Disconnecting the rear blower restored the horn and lights to normal operation. Anyone ever heard of such a thing, or know of a fix? Thanks