The AT-520-40 specifically includes the adjustment knob

This HVAC blower relay is critical for maintaining proper sequence of operation

Versatile Application: Compatible with various brands including Ruud

OEM Precision: Genuine Schneider Electric quality ensures tolerances match original equipment performance for critical damper and valve modulation

it requires a technician to physically investigate the cause of the overheat condition before the unit can be returned to service

Rheem-Ruud 47-20545-91 Switch R-410A The AT-520-40 specifically includes theThe Rheem Ruud 47 20545 91 Switch is a high precision 5 inch fan and limit control designed for critical thermal management in forced air furnaces. Engineered to handle a manual reset safety protocol, this limit switch features a 100 250F temperature range, ensuring the blower motor engages once the heat exchanger reaches 100F and triggers a safety cutout if temperatures exceed the 250F threshold. For contractors performing a furnace limit switch