Why does turning on the light of my ceiling fan/light fixture trip my circuit breaker?

I had a Harbor Breeze ceiling fan in the kitchen, lights and fan worked fine. One day, the fan stopped working. I attempted repairs with no luck, so I bought a new fan. Admittedly, I purchased almost solely on price- needed something cheap in a hurry. I got another Harbor Breeze fan, but the cheapest 52" they sell (Armitage - Builder's Series). I installed it exactly the same as the previous was installed with black (fan) and blue (light) to the hot wire and white to the neutral. The fan works fine but when I pull the chain to turn on the light it trips the breaker. Electric is old in my house (most is knob and tube), but I've never had any other limitations with it. Why would using both light and fan on this new unit trip the breaker when it didn't using both light and fan on the old unit?