Why Shouldn't You Try To Solve Low Voltage HVAC Electrical Issues Yourself?
Your home's HVAC system utilizes several electrical connections. Mains power, also known as supply voltage, comes from your home's service panel and supplies the electricity needed to run components such as the control board, AC compressor, furnace igniter, and so on. This supply typically comes in on a dedicated 220/240-volt line for central heating and air conditioning systems.
However, your HVAC control board also supplies power to several other components in your system.