The signal readout of a magnetoresistive (MR) transducer is very sensitive to temperature. To study the thermal effects on the MR transducer when the slider flies close to the surface of the disk, we introduce a heat transfer model with discontinuous boundary conditions in the thin slider/disk air bearing and solve it numerically. It is found that the heat flux is primarily due to heat conduction, which transfers heat from the slider to the air bearing when the slider has a higher surface temperature than the disk, and viscous dissipation, which transfers heat from the air bearing to the slider. Whether an air bearing acts as a ＇coolant＇ or ＇heater＇ depends on which part, the heat conduction or viscous dissipation, dominates the heat transfer. Since the magnitude of viscous dissipation is relatively small, the ＇heating＇ effect often plays a weaker role unless the temperature difference between the slider and disk is very nearly equal to zero. Simulation results show that the effect of the heat conduction increases with a decrease in the flying height, but the effect of the viscous dissipation decreases with a decrease in the flying height. In other words, the ＇cooling＇ effect increases with a decrease in the flying height.