Dual pass air conditioning unit

A method of reconfiguring a return air conditioning device configured to condition facility return air to an air conditioning device configured to condition outside air, the method comprising:

• partitioning an air output side to a downstream side of a cooling coil system of the return air conditioning device to create a pre-conditioned air passage chamber and a post-conditioned air passage chamber, the post-conditioned air passage chamber comprising an air exit aperture to supply conditioned air to the facility;
• relocating an air entry aperture from an upstream side of the cooling coil system of the return air conditioning device to the pre-conditioned air passage chamber such that the upstream side of the cooling coil system of the return air conditioning device comprises a partially-conditioned air passage chamber configured to accept air routed through the cooling coil system from the pre-conditioned air passage chamber and to route the air back through the cooling coil system to the post-conditioned air passage chamber;
• adding the return air in the partially-conditioned air passage chamber;
• and
• routing the return air from the upstream side of the cooling coil system adjacent to the partially-conditioned air passage chamber through the downstream side of the cooling coil system into the post-conditioned air passage chamber.