My heater switch works sometimes and then not at all other times.It is a blazer

The switch on dash that turns heater on and off

Ok let me re-word that; The blower, the temperature adjustment switch, is the blower not working or is the blower working but not getting warm air. Be more specific, or no one can help you without moving a switch for themselves to see what is not happening.

the switch itself to turn the heat on works intermittenly. Sometimes I start and it turns on other times nothing