The cold air blower is not producing any air at all, it doesn't sound it's doing anything.
The dashboard warning light showing on this page (or one very similar, sometimes a slightly different shape or colour) has appeared on the dashboard and doesn't go off when the car is running.
The engine temperature reading on the dashboard gauge is noticeably higher than usual. It doesn't seem to be caused by sitting in traffic on a hot day, it is generally just higher all the time.
The heater does not come on at all, the controls make no difference, there is no sound or hot air coming from the heater.