Had the weirdest thing happen last night on my way to work. A half hour into my commute that heater started blowing cold air. So this morning on my way home, it worked again for 1/2hr then went cold. If I shut the blower off and leave it off for a few minutes then turn it on I'll get about 15 seconds of hot air then it goes cold again.
Just had an oil change and they s'posedly filled up the fluids, coolant overflow tank is pretty much empty. Checked the oil and there's no coolant in it (thank Heavens).

Any ideas????

Thanks.
E