An indoor unit (1000) for an air conditioner is provided. The indoor unit (1000) includes a housing (100) having an upper base plate (110) provided with an air inlet (101), a lower base plate (120) detachably mounted to the upper base plate (110) and provided with an air outlet, and a front cover (130) detachably mounted to the upper base plate (110); a heat exchanger (140) mounted to the upper base plate (110); and a fan (142) detachably mounted to the lower base plate.