I have an a/c unit that is blowing on high speed.There are 3 wires:black, red,blue,white(and 2 brown for the capacitator)To reduce the speed from high to medium do I just disconect the high speed wire(black)?

Unhook the power wire from the black motor wire and use the blue motor wire in its place
or if it is on a terminal board move the wire that is powering the black wire to the blue wire
never hook more than one speed together
in other words whatever wire is now powering the the black high speed wire
take that wire FROM the high speed black wire and hook it to the blue medium speed wire leaving the black motor wire isolated



blue is medium
red is low
white remains where it is

The reason the a/c is on the high speed is to move the air because cold air is harder to move, slowing down the speed may cause your a/c to freeze-up. You can try changing the speed by reading the wiring schematic, take your time to become confortable with the schematic, and it will tell you which wire color conforms to each speed, locate the high speed wire color, and you will find that connected, locate the medium speed wire color, then disconnect the high speed and reconnect the medium speed wire in it's place. Be sure to tape the end of high speed wire so that it is insulated from the cabinet. ABOVE ALL MAKE SURE THE POWER SWITCH IS OFF BEFORE ATTEMPTING THIS