the small switch located on the side of the evaporator core. it has a tube running to the core. it probably is the cut off switch to monitor the temp and not let it get too hot or cold (freeze up) so. will the air work without it? will it get too cold and freeze up, or stay too warm and not cool enough, or have no or little effect at all. so... what do you think and what do you KNOW> ?? im asking cause i don't know.