Abstract: A method for preventing an evaporator of an air conditioner from freezing comprises the steps of (1) detecting an outdoor temperature, (2) determining whether or not the outdoor temperature is 20.degree. C., (3) determining whether or not the outdoor temperature is in a first temperature range, (4) determining whether or not the outdoor temperature is in a second temperature range, (5) varying an R.P.M. of the motor assembly based on the outdoor temperature detected in steps (3) and (4), (6) detecting a surface temperature of a condenser and determining whether or not the surface temperature of the condenser is in a third temperature range, (7) repeating steps (1) through (6) if the surface temperature of the condenser is higher than the third temperature range, and (8) rotating the motor assembly at a low speed if the surface temperature of the condensor is lower than the third temperature range.