No heater fan in all switch positions

The air temperature control blend door is sticking in the heater or neutral position.

Check fan relay.Turn heater and fan on turn ignition to on position then pull up on fan relay if does'nt click replace relay.

theirs a restriction in one of the hoses or the water pump is failing

Hook direct power to the fan and see if it works, if so, fan likely okay.

Yes I would go with the switch, BUT, does it have a resistor bank? That is, how does it reduce the speed? Many systems use resistors to lower the speed. Burnt or bad connections can cause this as well.
You can test the blower motor by connecting direct power from a source like the cigarette lighter if you are handy.
Most of the time the lower speeds konk out but the high speed continues to work this is the resistor bank that goes out.

it is must likely your fan control model -it control's
the fan speed location of model is next to blower

1) Check for +12v power from the fan select switch at the resistor pack - (If +12v is available there you may again have a faulty resistor pack).
2) Apply +12v directly to the fan motor to check that it runs ok.

Hi
Check for bad connection at heater resistor or try tapping heater motor lightly
with ignition switch on and heater switch on. Could be heater switch connection.

If the heater fan on your car only works on "High" the problem is more than likely the resister assembly in your blower circuit or poor connections at the resister assembly. When the switch is in the "high" position the current does not flow through the resister assembly it flows directly to the coil of the blower relay. When the switch is in "low", "medium 1", or "medium 2" position the current flows through 1, 2, or all 3 of the resistors in the resistor assembly which results in the 3 different lower speeds. Check the resister assembly and replace if needed. 

I suspect the ignition switch is malfunctioning.