blower moter only works on high what is the problem

There are many possibilities what could be effecting this condition and way too many to be guessing on. It is possible to be something as simply a a resistor module but the wiring and other components need to be checked first. If you want to get this problem diagnosed professionally, please call us , (313) 208-7752 or schedule your appointment on line at StansGarage.net. I am sure we can diagnose your problem and give you the answer you need. Larry