Things You'll Need
Socket wrench set
In order to properly adjust the pulley on a swamp cooler, the cooler belt should have no more than 1 inch of movement when you press down on the belt. You can adjust the pulley that is on the side of the motor by moving it along the motor bracket. Proper pulley adjustment will help increase the life of the belt and keep your cooler running efficiently.
Turn the breaker switch to the swamp cooler off at the breaker box before attempting to adjust the pulley. Take the cooler panel off the back of the unit by lifting it up and away from the cooler.
Determine whether the cooler belt is too loose or too tight before adjusting the pulley. Loosen the bolts on the motor bracket with a socket wrench just enough to be able to move the motor and pulley on the bracket.
Set the motor and pulley at the right position with a small prybar and tighten the bolts with the socket wrench when you have the pulley adjusted properly.
Place the back panel on the swamp cooler and flip the breaker switch on at the breaker box.
To avoid injury, always shut off the breaker switch for the swamp cooler at the breaker box before attempting to adjust the pulley.