Heating

I have a 1999 lumina. For the last 3 months i have not had any heat in my car. Only after driving nearly 30 miles it will heat up for a short period of time.(around 10-15 seconds) My water pump has had a leak in it since October. I know the consequences of not getting it fixed already and all but im in college and really nothing i have been able to do about it. I really never worried about this till this morning when i couldnt make it to class because the inside of my window had ice on it. With no way to heat the ice i was not able to make it in to school. So im wondering if anyone could give me the reason my heater is not heating inside my car and a cheap solution.

you check the radiator?>

i had the same problem on my 540i.

you check the radiator?>

i had the same problem on my 540i.

No problems with my radiator. Just the water pump leaks bad. So generally i dont have much fluid in it but i really couldn't afford a new one till the other day. I need to put it on later tonight after work. I thought that maybe the problem but i want to check and make sure.

Heater core probably airlocked from running low on coolant, or water pump has ceased to circulate the coolant.