A cartridge assembly for use in an aerosol-generating system, the cartridge assembly comprising: a cartridge comprising: a first compartment having a first air inlet and a first air outlet ; and a second compartment having a second air inlet and a second air outlet ; a housing enclosing the cartridge , the housing comprising: an upstream housing end wall comprising a third air inlet and a fourth air inlet ; and a downstream housing end wall comprising a third air outlet , a fourth air outlet , and at least one guide slot ; a mouthpiece comprising an upstream mouthpiece end wall and a mouthpiece air inlet in the upstream mouthpiece end wall , the mouthpiece air inlet in fluid communication with the third air outlet and the fourth air outlet ; and at least one linkage extending through the at least one guide slot and connected to the cartridge and the upstream mouthpiece end wall ; wherein the mouthpiece and the cartridge are rotatable with respect to the housing from a first position to a second position; wherein, when the cartridge is in the first position, the upstream housing end wall obstructs the first air inlet and the second air inlet , and the downstream housing end wall obstructs the first air outlet and the second air outlet ; and wherein, when the cartridge is in the second position, the third air inlet is in fluid communication with the first air inlet , the third air outlet is in fluid communication with the first air outlet , the fourth air inlet is in fluid communication with the second air inlet , and the fourth air outlet is in fluid communication with the second air outlet . a cartridge comprising: a first compartment having a first air inlet and a first air outlet ; and a second compartment having a second air inlet and a second air outlet ; a first compartment having a first air inlet and a first air outlet ; and a second compartment having a second air inlet and a second air outlet ; a housing enclosing the cartridge , the housing comprising: an upstream housing end wall comprising a third air inlet and a fourth air inlet ; and a downstream housing end wall comprising a third air outlet , a fourth air outlet , and at least one guide slot ; an upstream housing end wall comprising a third air inlet and a fourth air inlet ; and a downstream housing end wall comprising a third air outlet , a fourth air outlet , and at least one guide slot ; a mouthpiece comprising an upstream mouthpiece end wall and a mouthpiece air inlet in the upstream mouthpiece end wall , the mouthpiece air inlet in fluid communication with the third air outlet and the fourth air outlet ; and at least one linkage extending through the at least one guide slot and connected to the cartridge and the upstream mouthpiece end wall ; wherein the mouthpiece and the cartridge are rotatable with respect to the housing from a first position to a second position; wherein, when the cartridge is in the first position, the upstream housing end wall obstructs the first air inlet and the second air inlet , and the downstream housing end wall obstructs the first air outlet and the second air outlet ; and wherein, when the cartridge is in the second position, the third air inlet is in fluid communication with the first air inlet , the third air outlet is in fluid communication with the first air outlet , the fourth air inlet is in fluid communication with the second air inlet , and the fourth air outlet is in fluid communication with the second air outlet . <EOS>