English to Portuguese Tech/Engineering Electronics / Elect Eng air conditioning

"Single-circuit control of centralized air-conditioning systems with 1 or 2 compressors (steps)..."

Again, the term appears in a manual of a control board for air conditioning, in the section where it describes the main functions of the board.In the original version, in Italian, it's translated as

"Controllo di unità centrali per il condizionamento a un solo circuito, con 1 o 2 compressori (gradini) del tipo..."

Now, I've looked for, and I can't find any references to " (...) com 1 ou 2 compressores( passos)" in PT. Could "steps/gradini" here be something in the lines of " com 1 ou 2 compressores (níveis)", as in 2 different compressors or 2 different types of compressor operations?

Thank you for all suggestions