Took the car out to the movies tonight. The heater seemed to work ok on the way there, except for making noise. The predominant noise is like 'tinkling china' as my wife describes it. The other major noise is a vibration sort of like a hard drive running on a computer. Every once in a while there is also a groaning like a duct door opening or closing too slow or too tight.
On the way home from the movie, I couldnt seem to get the heater working at all. (although I could feel a bit of hot air coming through the defroster outlets when the car was moving). No matter what position the buttons were in, whether the fan was on high or auto, nothing made a difference. I pulled in the garage, opened the door and went to pull on the lever to open the hood, and all of a sudden the fan came on high, blowing hot air.
I did check coolant level and it is halfway up the fill reservoir, so it looks ok.