This study investigated the temperature and viscosity distributions within the heat block of an FDM printer capable of printing PEEK (polyether ether ketone) filament, under the influence of cabinet temperature, using the finite element method in the ANSYS environment. The results were tested using a temperature-controlled, air-cooled FDM (Fused Deposition Modelling) printer (TR Patent 2021 018438 B) for printing PEEK filament and the optimum airflow rate for cooling was determined for different cabinet temperatures. PEEK filament with a melting temperature between 450 and 500 °C and a bed temperature between 100 and 150 °C was used in the analysis. The outdoor temperature was set to 24 °C and the cabinet temperature was varied from 50 to 120 °C. The filament was tested to ensure it flowed smoothly through the heat block at these temperatures. A viscous laminar flow model was employed for the finite element flow analysis, with a piecewise linear method chosen to describe the temperature-dependent viscosity of the PEEK material.