Air Filter
Filter ratings, pressure drop and airflow problems.
AC Leaking Water Inside: Condensate Drain, Float Switch and Pan Problems
Why an air handler or furnace coil leaks water indoors, how to find the cause fast, and how to clear and protect the condensate drain so it doesn't come back.
AC Short Cycling: Why the Compressor Turns On and Off Too Often
How to diagnose an air conditioner or heat pump that short cycles, using how long it runs and what stops it: thermostat problems, safety switches, low charge, airflow, and oversizing.
Furnace Temperature Rise: How to Measure It and What the Reading Means
How to measure furnace temperature rise correctly, where the normal range comes from, how to estimate airflow from it, and what a high or low rise tells you.
AC Not Cooling? A Step-by-Step Diagnostic Checklist for Techs
Work an AC no-cool call in the right order, from the thermostat call to airflow, electrical and refrigerant charge, without guessing.
Frozen Evaporator Coil: Causes, Safe Thawing and What to Check
Why AC evaporator coils freeze, how to thaw one safely, and the order to check airflow, charge and metering once it's thawed.
Furnace High Limit Switch Tripping: Causes and How to Fix It
Why a furnace's high limit opens, how to confirm it with temperature rise and static pressure, and when the switch itself is the problem.
MERV Ratings and Filter Pressure Drop: Picking a Filter That Won't Choke the System
What MERV ratings mean, how filter pressure drop affects airflow and static pressure, and how to choose a filter without restricting the blower.
Total External Static Pressure: How to Measure It and What's Normal
Measure total external static pressure with a manometer, compare it to the equipment's rating, and use it to find airflow restrictions.