A/C Heater fan stays on the high setting only. Every thing else works.

AT STACKS AUTO WE CAN CHECK IT OUT FOR YOU AND GIVE A ESTIMATE ON FAN STAYING ON CALL US AT 631-422-4010 OR 631-539-0930

Do you mean the fan only works on the max high speed? If so the fan resistor may have failed not allowing the lower speeds to operate. Please be more specific if I misunderstood your question.