this SF series unit features a 48 cubic inch filtration area

or if the frame is warped

for proper 3-7 PSI operation

the 387210R is the official superseded part number for the 387210

As a direct 100208551 replacement part

Carrier HH680405 Limit Switch Refrigerant this SF series unit featuresThe Carrier HH680405 Limit Switch is a critical safety component designed for precise thermal regulation within high performance HVAC systems. Engineered as an Auto Limit Switch, this part features a broad operating range of 30 250F, making it a versatile OEM replacement part for Carrier, Bryant, and Payne furnaces. As an HVAC high limit switch, it monitors discharge air temperatures to prevent heat exchanger damage or hazardous operation. Its