My daughter just called from college, her heat.

Many things can cause the light to come on. And yes, some are safe to drive with and others are not. What I suggest is to take the car to a nationally recognized parts store and have them scan the computer. Most will do it for free. Then come back to me with the code they find and I will be better able to answer your question. As far as the heat, is the blower motor not working or is it just blowing cold air? Have her make sure the coolant is full.

Let me know what you find.