I was changing Cabin filter for my 2001 MDX, I noticed noise coming from small unit attached to coil unit where you change the filter, it has green plug, I disconnected that plug and noises stopped, I pluged it back and that noise came back ON, even when AC is OFF, does anyone know what this unit is? its the first unit on the left from cabin filter, someone said, its the blower, but when I disconnected the Plug AC and heater were working fine, so I don't think its the blower, please help?