How do I fix this? Someone said something to me about the heater core, but I seriously know almost nothing about this car as far as how to fix things. Any help would be appreciated, as I keep trying to drive at night without a defroster, and it's really hard.

 

If it's the heater core, then you can google how to replace it, there's been writeups on here as well. The heater core is behind your glovebox

 

Is it just clogged maybe, or probably broken?

 

Check to make sure you have sufficient coolant in your radiator. It should be filled to the top. Not the plastic reservoir but the radiator. Your radiator needs to be full for you heater to work properly.

An air bubble trapped in the system can cause problems too. You can run your engine without your radiator cap on to bleed the system but it takes a while and makes a mess. You run it till it gets to operating temperature and then the thermostat opens allowing the cycle of coolant to circulate around the engine, through the heater core and the radiator. Allow to run for a few minutes and any air bubble in there will be pushed out.

If this doesn't work your heater core is probably clogged. You could try to flush it but if it's clogged you most likely want to replace it. Not an easy job on any kind of vehicle.