On an energized, intact circuit, you will read voltage across an OPEN switch when testing with a voltmeter. However, you probably won't read significant voltage across a CLOSED switch. Both sides of a closed switch are electrically identical (or at least very close). Therefore, there should be no movement of electrons between the leads of […]

Airflow, airflow, airflow… When we set up and commission comfort cooling and heating systems, we need to pay more attention to airflow before worrying about the fancy controls or the refrigerant circuit. So, as a thought exercise, let's consider a typical 2-ton, straight cool, TXV residential system and think through what happens when we alter […]

The title says it all. It should be one of the first things you learn when you started. However, I have seen a lot of experienced techs who seldom (if ever) do it. When connecting to a tank, purge your hose by cracking the center connection at the manifold for a second. When connecting to […]