The "Y" terminal on a thermostat typically controls what function?

The "Y" terminal on a thermostat is specifically designated for controlling the cooling system. When the thermostat calls for cooling, it sends a signal through the "Y" terminal to the connected air conditioning unit or heat pump, activating the system to cool the indoor environment. This is a critical function in maintaining comfortable indoor temperatures during warmer weather.

The other options involve different components or aspects of HVAC systems. Heating is usually controlled by a different terminal, often labeled "W". Fan operation is typically managed by a terminal labeled "G", while humidification functions are usually connected to specific humidistat control and not directly related to standard thermostat terminals. Understanding the role of each terminal helps ensure proper installation and troubleshooting of HVAC systems.