The typical sequence for cleaning an HVAC system is return, air handler, and then supply. This sequence ensures that contaminants are removed in the direction of airflow, starting from where air enters the system (return) to where it is distributed (supply). Cleaning the air handler in between ensures that the central component of the system is cleaned before air moves through the supply ducts.

When a properly wired condensate pump fails, it will turn off the HVAC system. This safety feature prevents water damage or overflow by stopping the HVAC system if the pump or its associated components are not functioning correctly.

The most effective way to test the function of a condensate pump is to fill the condensate pan with clean water. This method allows the pump to operate under normal conditions, ensuring that it can properly activate and pump out the water as it would in a real-world scenario. Unplugging and plugging in the pump, disconnecting the condensate drain line, or filling the pump with water directly do not simulate normal operational conditions and might not effectively test the pump's functionality in actual use.

In a Constant Air Volume (CAV) system, changes in temperature are achieved by heating or cooling the air. The airflow rate remains constant, while the temperature of the air being delivered to the space is modulated to maintain the desired indoor conditions.

When a condensate pan is full of water, the first thing the ASCS should check is the drain line. A full condensate pan usually indicates a potential issue with the drainage system, such as a blockage or a malfunctioning drain line. Ensuring the drain line is clear and functioning properly is essential before investigating other causes such as coil leakage, pan slope, or plenum pressure.