Hello all and thanks for allowing me to join. I have a current problem with my a/c. It only operates on speeds 3 and 4 (med high and high). Any clues as to what may be causing this and how to fix it. somewhat mechanically inclined but not certified.

 

Usually the high speed setting is handled by a separate relay.
All other speeds go through a resistor.
I would suspect the blower motor resistor is defective.
Not difficult to change.If you aren't sure what it looks like , get a new one and now you will know what to look for under the hood usually located on the evap ductwork.
Some are held with 2 screws , some with 3 screws. The resistor body has a plug with 3-4 wires on it. Usually easy to replace.

 

Thanks hanky. That cured the problem, a/c works like a charm now.