What's that part?

[Mark57]

1986 Corolla 4AC Auto 2bbl
Located behind the glove box and attached to the heater core box is a component with a 12 pin connector going to it. On top is an adjustment knob with corresponding markings of H...........RPM............L. Anyone have an idea about what this adjusts the speed on? Tore my Haynes apart looking for it - no luck.

Thanks, Mark

[uraverageyota]

its called an ac amplifier, dooes your ac compressor have a revolution sensor mounted on the rear of it? Should be a 2 pin conector if it does. The amplifier can be adjusted to keep the compressor clutch engaged a bit longer or less. But the 4A/C motor should have a 10 pin connector with only 9 pins being used. 4A/GE motor 14 pin connector w/13 pins being used.