The fire ignited due to air conditioner (A/C) malfunctioning is studied numerically for a single room, two rooms with interconnection, two interconnected rooms with attached corridor and a two-storeyed building with stairs. Coupled finite difference and finite volume based open source solver, Fire Dynamics Simulator (FDS) is used for domain discretization and solution of governing equations. Heat release rate per unit area (HRRPUA) is varied in the single room case and temperature and visibility contours are studied to determine HRRPUA corresponding to maximum hazard, judged based on available safe evacuation time (ASET) calculation. Further, positions of air conditioners, at a prescribed HRRPUA, are varied in two interconnected rooms to obtain the case with maximum ASET. Evacuation strategy is discussed and the maximum number of persons who can be safely evacuated from the accident site is calculated followed by the variation in the position of doors in the case with inter-connected doors attached with a corridor. Soot flow pattern and flame contours are also observed for each of the above cases. At the end, fire breakout is simulated in a two-storeyed building with stairs and having the room configuration based on the maximum ASET value.