If the motor has a starting capacitor on it, there should be some leads marked T5 and T8. Swap these two wires. If they are not numbered,they may be color coded. There could (should) be a legend plate on the motor to identify which two leads to change. Look inside the wiring junction box also for information. If it doesn't have a starting capacitor, you may need to take it to a motor rewind shop to get it changed. In some instances, you can change ends of one of the windings internally to do this.