When must an installer ensure that the cabinet is plumb and its sides are vertical?

The installer must ensure that the cabinet is plumb and its sides are vertical when changing out an evaporator coil because the proper installation of the coil is critical for system efficiency and performance. If the evaporator coil is not level, it can lead to improper drainage of condensate, causing water leaks or flooding within the unit. Additionally, an unlevel coil may affect refrigerant flow and heat exchange efficiency, resulting in diminished cooling capacity and potential strain on the HVAC system.

Maintaining the vertical alignment of the cabinet also contributes to the overall structural integrity of the setup, ensuring that components fit correctly and operate as designed. Proper installation practices help in preventing issues down the line, such as high maintenance costs and system failures, thereby promoting reliable operation and longevity of the heat pump system.