Just to make sure I understand you: Do you have air but it's not hot, or you don't have air at all?
IF you don't have air at all:
Have you tried all the fan speeds?
If the fan does come on but at high speed only, suspect bad blower resistor.
If the fan doesn't come on at all no matter the speed, check your fuse and relay first.
If they're good, you probably have a bad blower motor.
If you do have air but it's not hot:
Check your level of coolant first
Check your thermostat (is your engine taking a long time to reach normal operating temperature? If so replace thermostat)
With car idling at normal operating temperature and heat set on high, feel the two heater hoses under the hood (the two small hoses hooked to the heater core inlet and outlet on the firewall). Are they both very hot? If one is much colder than the other, suspect clogged heater core.
You could have too much air in the system; it usuallly result in intermittent heat, but you never know: bleed the cooling system.
There is also a chance that your blend door actuator or the blend door itself is bad. If you troubleshot everything mentioned above and still can't find what's wrong,
Hope this help; come back if you need more help.
Tuesday, November 25th, 2008 AT 10:20 AM