Cooling system of modular data center (MDC) has air handling unit (AHU) that circulates cooling air through information technology (IT) module(s). Transducer(s) sense first air characteristic value of cooling air directed to IT module(s) of MDC, the value being selected one of: (i) temperature value; and (ii) humidity value. AHU controller determines whether first air characteristic value satisfies first air characteristic criterion of one of: (i) a temperature value equal to or greater than minimum temperature threshold; and (ii) a humidity value equal to or less than maximum humidity threshold. In response to determining that first air characteristic criterion is not satisfied, AHU controller triggers supplemental heater to warm cooling air before cooling air comes into contact with IT module(s) inside of MDC to at least one of: (i) provide cooling air above minimum operating temperature of components within IT module(s); and (ii) prevent condensation.