Abstract: Systems and methods for monitoring the performance of an HVAC unit are disclosed. These systems may include a suite of indwelling sensors that are placed within the HVAC unit. The sensors themselves are battery-powered, have energy-efficient components, and communicate wirelessly with a sensor controller. The sensor controller controls the sensors and bridges between local wireless communication with the sensors and wide-area wireless communication to report sensor data to a monitoring station. Control methods for these sensors include instructing them to take and report data only at defined intervals.