Reversible airflow in cooling systems of electronic devices is described. For example, an electronic device may include a reversible fan tray. The fan tray may include symmetric mounting features that allow the fan tray to be mounted in the electronic device in more than one orientation at the same location within the electronic device such that one or more fans in the fan tray either direct air into the electronic device or to pull air from electronic device. The fan tray may further include a symmetric arrangement of connectors that coincide with the symmetric arrangement of mounting features to allow the fan tray to be connected to a power source of the electronic device any of the more than one orientations. An arrangement of electronic devices including reversible fan trays may be configured so that inlet and outlet airflows are separated to increase cooling efficiency of the electronic devices.