Refrigeration and HVAC runs on pressure, and the sensor that reads it has to live in a compressor room where the housing sweats, the wiring harness is crowded, and a service call means the machine stops while a tech fumbles with cable glands. The YCQC05L20 is the Korean-built answer to that service model: M12 connector in one hand, wrench on the 7/16-20 UNF thread in the other.

Why a piezoresistive cell with a -1 bar lower range on a compressor?

Because a compressor inlet or a heat-pump suction side does not just see positive pressure - it pulls vacuum, and a cell that bottoms out at 0 bar cannot tell suction from a blocked filter. The -1 to 50 bar range covers both suction vacuum and discharge pressure in one transmitter, the piezoresistive silicon cell holds 0.5% accuracy across that span, and the 4-20 mA signal over 32 VDC drops straight into the existing controller. The M12 connector is the service detail: twist it on and walk away, no gland, no soldering.