Frost formation is one of the primary causes of performance degradation in refrigerators, air conditioners, and water heaters that operate on vapor compression technology. Defrost cycles are energy-intensive and highly dynamic operations embedded within the system’s control strategy, influencing both the refrigerant cycle and the airside flow rate. As a result, their characterization increases the complexity of reproducing dynamic performance tests. This paper presents a feedforward compensation technique based on the development of a transfer function model for real-time recalibration of the room emulator’s control signal to the reconditioning unit in the testing facility. The proposed method introduces no additional equipment cost and demonstrates broad applicability. Experimental results show that the method effectively reduces offset and delay in tracking the return air condition within 60 s across various test scenarios in heating mode. It also improves test reproducibility, limiting performance deviations to within 2%, and ensures closely matched control parameter modulations during load-based testing. Overall, the proposed method enhances the reliability and clarity of defrost operation investigations and supports control optimization aimed at minimizing performance losses due to frost formation.