Fan blows, radiator in car is getting hot. There appears to be a valve that switches the coolant off and on next to the firewall that moves freely when you remove the control cable. The heater core is not leaking inside the car. A couple of times when the car was started on cold mornings the heat did come on briefly, but beyond that, it does not work. We live in South Lake Tahoe, it is snowing like crazy and we do not have the money to pay someone to diagnose this. If I knew what it was, I could probably fix it my self. We have to scrape the ice off of the inside of the windshield just to see (barely). If anyone knows what the problem is, help would be greatly appreciated.