These are some general HVAC service techniques I've picked up over the years, and I've written this article hoping these tips will help technicians who are just starting out in our trade.
If you're looking for a more detailed, step-by-step troubleshooting guide, you might want to take a look at my article "Air Conditioning Troubleshooting" in the Service & Maintenance archives of The NEWS' Extra Edition page. Just click on Service & Maintenance in the left column to find the article.