Abstract: A control system measures the pressure/temperature of the refrigerant within a Thermal Energy Module having a heat exchanger and calculates the thickness of ice within the Thermal Energy Module. A controller calculates an integral starting from the moment when ice accumulation begins: I(t)=?Tr(?)*d? where Tr is the refrigerant saturation temperature changing with time t. The thickness of the ice on one side of the heat exchanger can be calculated using the following formula: X=?(2*I*K*Ui/?i/ci) where Ui is the thermal conductance of ice ?i is the density of the ice Ci is the latent heat of the ice K is a correction coefficient associated with the type of the heat exchanger.