When performing service

Chemical Compatibility: High-grade Viton seals allow for the safe handling of various media

and O-rings—to complete a standard first check overhaul

preventing the control board from sending voltage to the gas valve

including the 21TC and AUC series

Carrier HH18HA498 Limit Switch 319825-402 When performing serviceThe Carrier HH18HA498 Limit Switch is a high precision OEM furnace limit control engineered for critical thermal regulation in Carrier, Bryant, and Payne heating systems. This disc style limit switch functions as a primary safety mechanism, featuring a normally closed circuit that opens on temperature rise to prevent heat exchanger damage or hazardous operating conditions. With a factory calibrated operating range of 170 210F, the switch is designed