Temperature control has gotten more complicated as manufacturers get more innovative and consumers get more demanding.
HVAC systems have come a long way in the past 15 years. While the basics of heating and cooling may be the same, the controllers and sensors have improved dramatically.
Instructor Dave Hobbs gives some insight into something a lot of techs already know about and may just take for granted–two stage temperature sensors. He covers some specifics about the sensors, testing procedures, and how to avoid replacing parts that are good only to find you still have a problem. He also gives some details and insight into the differences in design and wiring of these sensors between the individual manufacturers.