The present study concerns an experiment on the heating characteristics of a system air-conditioner (A/C) using PWM method or inverter method at low temperature con-ditions. The compressors used are digital scroll type and BLDC inverter type. Under the low outside temperature condition, -5$^{circ}C$, -1$0^{circ}C$, -15$^{circ}C$, heating capacities and COPs are mea-sured by the psychometric calorimeter using air enthalpy method. Also, outlet air temperatures at heating operation mode are measured at -5$^{circ}C$, -1$0^{circ}C$ and -15$^{circ}C$. Experimental results show that COPs of the system A/C using a PWM method are more effective than those of the inverter method at heating operation mode. Although the heater is on, COPs of PWM method are similar to those of BLDC inverter method. Moreover, the heating capacities of PWM method at -5$^{circ}C$, -1$0^{circ}C$ and -15$^{circ}C$ are larger about 10~20% and outlet air tempe-rature at -15$^{circ}C$ is larger about 10%, compared to the inverter method.