Conditioning systems and methods for providing cooling to a heat load can include an evaporative cooler arranged in a scavenger plenum with a recovery coil downstream of the evaporative cooler. The conditioning systems can operate in various modes, including an adiabatic mode and an evaporative mode, and a blended mode between the adiabatic mode and the evaporative mode, depending on environmental conditions. The blended mode can be enabled by a fluid transmission and retention device fluidically connected to the inlet and outlet of the evaporative cooler, the recovery coil outlet, and the heat load. The fluid transmission and retention device can variably distribute the cooling fluid exiting the recovery coil and the cooling fluid exiting the evaporative cooler to one or both of the heat load and the evaporative cooler inlet. In an example, the fluid transmission and retention device includes a manifold. In another example, the fluid transmission and retention device includes one or more tanks.