This article is part 3 in a 5-part series by Senior Refrigeration and HVAC Technician Jeremy Smith.

Let's start with step#1 in the flowchart:

Gather data.

This is why we spend money on those fancy digital manifolds, shiny electrical meters, and other gadgets, widgets, and doodads. It isn't to brag about them on Facebook; it's to find problems better and faster than someone else.

So, before you start trying to change things, start by gathering and recording data. Inspect filters, inspect coils. Look over the wiring. Check your voltages, resistances, airflow, pressure readings, temperature readings. Locate any open switches in the control circuit, and try to determine WHY that switch is open. A pocket notebook is nice, but for larger problems, I've taken to carrying a full-sized college-type notebook.

This gives me more room on the page to write my notes, draw pictures, scribble thoughts, and observations about the equipment I'm working on.

Write down every measurement and reading. EVERYTHING. Even if you find that capacitor blown up and you “just know” that's the problem, take your time and keep looking.

Before we leave the Data Gathering step, we do need to take whatever steps are necessary to get the equipment running if it isn't already and gather another set of data.

Once you have all this data together, we can proceed to Step #2: Analysis.

—Jeremy

If you've missed the previous parts of this series, here are the links to Part 1 and Part 2.