heater switces not working, only once in aq while what to repalce?

Sounds like your blower motor is bad. If you have no fan at all, it would be your blower motor. If you have only one speed all the time, it would most likely be your blower motor resistor. For a quick test, turn on your fan, if no fan comes on, take a hammer and tap on the bottom of your blower motor. If it suddenly come on, the brushes are bad in your motor. Usually located under passenger side glove box. Here's a quick video: http://www.youtube.com/watch?v=ymKzKOnI78s