Abstract: A method of controlling an output temperature of an air conditioning unit including acts of drawing an air flow into the unit to create an air flow through the unit, directing the air flow across a plurality of heating elements, including a first heating element and a second heating element, generating a first pulse width modulated (PWM) control signal, applying the first PWM control signal to a first contactor to control the first heating element to heat the-air flow, generating a second pulse width modulated control signal that is phase shifted from the first PWM control signal, and applying the second PWM control signal to a second contactor to control the second heating element to heat the air flow. Cooling systems and further embodiments are also disclosed.