In a two-stage cooling system, what happens when stage 2 is called?

In a two-stage cooling system, what happens when stage 2 is called?

• A. The thermostat issues a stage-2 cooling call, engaging the second-stage compressor and related controls.
• B. Stage 2 bypasses the first stage and runs only the outdoor unit.
• C. Stage 2 reduces indoor fan speed to compensate.
• D. Stage 2 triggers defrost mode.

Answer: (A)

Two-stage cooling uses two levels of capacity, and the stage-2 call is what brings the higher-capacity operation online. When the thermostat determines more cooling is needed than stage 1 can provide, it issues a stage-2 cooling call. This energizes the second-stage compressor and the related outdoor unit controls, letting the system run at higher capacity to meet the load. It also helps with humidity control and reduces frequent cycling, improving efficiency overall. It doesn’t bypass the first stage, it doesn’t slow the indoor fan, and defrost mode isn’t involved in normal cooling.

Two-stage cooling uses two levels of capacity, and the stage-2 call is what brings the higher-capacity operation online. When the thermostat determines more cooling is needed than stage 1 can provide, it issues a stage-2 cooling call. This energizes the second-stage compressor and the related outdoor unit controls, letting the system run at higher capacity to meet the load. It also helps with humidity control and reduces frequent cycling, improving efficiency overall. It doesn’t bypass the first stage, it doesn’t slow the indoor fan, and defrost mode isn’t involved in normal cooling.