it refers to the switch contacts closing when the negative pressure (vacuum) reaches the 1

Its strap-mount design is ideal for retrofit applications or systems where immersion wells are impractical

This evaporator-mounted thermostat features a 1000 mm capillary tube

Standardized Fit: Black color-coded spring allows for rapid identification during field service and inventory management

or if the contacts remain stuck closed (causing the "fan only" or "constant heat" symptom)

Carrier 30032021 Control Board Els PW 17895 it refers to the switchThe Carrier 30032021 Control Board is a critical OEM replacement part designed for high precision management of commercial HVAC systems and residential furnaces. This integrated circuit board serves as the central processing hub, coordinating essential sequences including gas flow regulation, ignition control, and blower motor speed. Engineered for high performance HVAC monitoring, the module utilizes a sophisticated logic controller to interpret real