My wall switch controls the fan speed, direction, and light. Recently, the only functions it will control is the light and the fan runs on full speed only. In other words, no control over fan speed or direction. The switch has one wire attached to the power source and other one goes to the fan itself. Is there any way to determine whether it is a faulty switch or could it be the receiving unit in the fan itself? The switch is available but rather pricey to be guessing.

BOB

my wall switch controlls the fan speed, direction, and light. Recently, the only functions it will control is the light and the fan runs on full speed only. In other words, no control over fan speed or direction. The switch has one wire attached to the power source and other one goes to the fan itself. Is there any way to determine whether it is a faulty switch or could it be the receiving unit in the fan itself? The switch is available but rather pricey to be guessing.

BOB
If there is a part of the switch that operates each piece, like one part of the switch does direction, the other part of the switch does fan speed then it is more than likely the switch. If you have a remote and the fan works fine with it, that's another indicator it's the switch. If you can operate the fan just fine at the fan, then it would be the switch. Most places will let you return the switch if you find out that's not what's working.

The last answer doesn't make any sense.. .

What make/model is the fan?