The Lennox 21P88 Adjustable Fan & Limit Thermostat is an OEM-quality HVAC control used to manage furnace blower operation and provide over-temperature safety protection. Designed with an adjustable fan temperature range of 90°F to 130°F and a fixed 20°F differential, this fan limit control ensures proper airflow timing while helping protect the furnace heat exchanger from overheating. The close-on-rise switching action allows the control to respond accurately as temperatures increase, supporting reliable and consistent system performance.

This fan and limit thermostat is commonly used in Lennox gas furnace applications and is suitable for both residential heating systems and professional HVAC service work. Built to meet OEM specifications, the Lennox 21P88 offers dependable operation, straightforward installation, and long-term durability. It is an ideal replacement part for maintaining safe furnace operation, efficient heat distribution, and proper fan cycling in HVAC systems.

Brand: Mars
Lennox Catalog Number: 21P88
Manufacturer Part Number: 39205
Type: Adjustable Fan & Limit Thermostat
Temperature Range: 90–130°F
Differential: 20°F
Switching Action: Close on rise
Unit of Measure: Each
UPC: 66255140285
Approximate Weight: 0.1 lb