the bimetal disc in the limit switch may have weakened over time

identical to the PUM30003

NEMA 3R Protection: Weather-resistant housing allows for outdoor installation and protects against condensation

designed specifically for heavy-duty residential and light commercial HVAC applications

Resideo AT40A1139 Transformer 322057-301 the bimetal disc in theThe Resideo AT40A1139 Transformer is a heavy duty 40VA power supply designed for reliable 24V control circuits in residential and light commercial HVACR applications. Engineered with a 240V primary and a 26. 5V secondary output, this NEMA Type D transformer ensures consistent voltage regulation for thermostats, zone valves, and gas valves. The channel frame mounting configuration allows for versatile installation directly onto a junction box or