verifying continuity on this primary limit control is a standard diagnostic step

Flexible System Control: The SPDT snap-acting switch manages both heating and cooling changeover logic within a single device

returning to its normal state once the ambient temperature falls back within the 70F to 80F threshold

Utilizing a genuine Carrier part prevents the common issues of airflow restriction or excessive noise associated with generic universal blades

Repeated actuation of the 165 degree limit switch usually indicates restricted airflow

Resideo PCV125 Check Valve 321702-401 verifying continuity on this primaryThe Resideo PCV125 is a professional grade 1 1 4" hydronic check valve engineered to eliminate ghost flows and reverse circulation in high demand residential and light commercial systems. Specifically optimized for AquaPUMP PC3F2699IUF00 series circulators, this inline flow check ensures directional stability in closed loop heating and chilled water applications. By maintaining a positive seal during pump cycling, it protects expensive boiler heat