Heater control only works on high

Can you tell that the fan is getting higher or lower? Or is there no response from the fan control until you get to the high position?

You should always make sure that the parts you put back are compatible with the parts you take off. If i am not mistaken, there is another fan resistor outside under the hood, and one inside under the passenger side dash panel, if your motor is inside. One outside is for high, and the one inside is for low, medium, and medium high. If you know for a fact both speed control resistors are good, replace the switch on the dash panel. To check to see if the dash switch is not making good contact, take the switch while it is still in, and on low, high, or medium, push the switch lever to the right or left gentlely to see if it makes any contact. These year model cars are notoriuos of having fan motor issues early........

Heater core is partially plugged or the control valve for the heater is not working.

you should make a diagnostic to know what happened to your car
of course you need an auto diagnostic tool : http://www.chinasnoy.comand you can find all kinds of tools in chinasinoy.com

either the switch or there is a resistor pack in the heater duct that gets burned out and only 1 side works if it is not the high medium low switch check resistor pack mounted in the heater duct.

Its not the switch or the controller in the instrument cluster. On my jeep there was a panel on the passenger side under the dash board. It helped me find it by turning on the heater and going toward the sound of the blower. On the backside of the panel was a series of little coils that control the different speeds. one of those coils had been broken.

There are two relays for the heater control fan,a low blower relay and a high blower relay.It sounds like the hi blower relay is bad.

change the blower resister module,if this doesnt work replace the control head

Either the blower went bad or the heater relay went bad. This does not sound like a heater core problem unless you where smelling a SWEET smell when it was running.

the heater resistor is gone change it hope it help fixya our post thanks pierre