This system is used only on carbureted vehicles.
This system consists of a throttle opener assembly, a solenoid valve, an engine speed sensor and a compressor switch for the air conditioner unit.
When the compressor switch is turned on and the speed sensor detects engine speed at or below its present level, the solenoid valve is opened slightly by the throttle opener. Consequently, the engine idle speed increases to compensate for the compressor load. When the compressor switch is turned off, the throttle stops working and returns to normal idle.