Active Magnetic Regeneration (AMR) is a configuration that allows magnetic refrigeration to be suitable also for room temperature applications. This work is intended to detect, by means of a 1-D numerical model, the influence on the regenerator performances of the working condition ambient temperature (T(CURIE) +/- 20 K) and of the operating parameters fluid mass flow rate (utilization factor 0.5 divided by 3.5) and cycle frequency (0.1 divided by 0.6 Hz). Simulations show that, tuning the fluid mass flow rate, a gadolinium AMR (395 g, f = 0.25 Hz, Delta B = 1.7 T) can reach a maximum cooling capacity of 130 W and a 40 W cooling power over a temperature span of 30 K. A COP of 5 can also be achieved with a temperature span of 30 K and a cooling power of 35 W. Frequency has a weak influence on the AMR's COP, while the ambient temperature is crucial. The system loses the 60% of cooling capacity if the ambient temperature is 20 K away from the material Curie temperature.