Development of a thermal imbalance between heating and cooling at the loop top location (x, y) = (3.14, 4) Mm in the late phase of our simulation. The red curve denotes the heating rate due to thermal conduction (H_con) and background heat (H_bgr), and the blue curve denotes the cooling rate due to radiation (H_rc). The units for all the quantities are in erg cm⁻³ s⁻¹. The vertical dashed line marks the time after which the radiative cooling starts to dominate the heating due to conduction and background heat.