2002 f=250 heater/ac blower will only run on high speed what is the fix thanks ?
few things, first, check fuses to see if it has high and low for the heater in fuse panel, second and most common problem, the resistor on the blower motor, that's most likely your problem. it's under the dash, passenger side. if that isn't it, heater control switch it bad. Most likely the resistor is bad.
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