AC Troubleshooting
No cooling, frozen coils, compressors and condenser fans.
AC Breaker Keeps Tripping: How to Find Out Why
How to diagnose an air conditioner or heat pump that keeps tripping its breaker: a grounded compressor, a locked rotor, a shorted fan motor, wiring faults, high head pressure or a weak breaker.
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.
How to Clean an AC Condenser Coil the Right Way
How to clean a condenser coil without damaging it, which cleaners to use on copper-aluminum vs. all-aluminum coils, how to tell when it's dirty, and what a dirty coil does to pressures.
AC Compressor Not Starting: Humming, Clicking or Nothing at All
Diagnose a compressor that won't start by what it does: humming points to capacitor or locked rotor, clicking to overload, silence to the control circuit.
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.
Condenser Fan Not Spinning: Capacitor, Motor or Control?
Find out why an outdoor condenser fan won't run, from the fan capacitor and seized bearings to the contactor, wiring and heat pump defrost.
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.
How to Find a Refrigerant Leak: Methods, Common Spots and the Standing Pressure Test
A step-by-step leak search for AC and heat pump systems, the leak detection methods and where each works best, the most common leak spots, and how to confirm the repair.
Replacing a Run Capacitor or Contactor: How to Pick the Right Part
How to choose a replacement run capacitor (µF, voltage, dual vs. single, size) and contactor (coil voltage, poles, amp rating), with the common mistakes that bring callbacks.
Thermostat Blank or No Power: Finding the Missing 24 Volts
How to troubleshoot a blank thermostat: batteries, the C wire, the furnace door switch, a blown board fuse, a tripped float switch, the transformer and power to the air handler.
400 CFM per Ton: Where the Rule Comes From and When It's Wrong
Why 400 CFM per ton is the default cooling airflow, when to set airflow lower or higher, and how to check what a system is actually moving.
High Indoor Humidity with the AC Running: Causes and Fixes
Why a house stays humid even with the air conditioner working, from oversizing and airflow to fan settings, duct leaks and ventilation.
How to Test an AC Contactor: Coil, Contacts and Voltage Drop
Test a condenser contactor the right way, from 24 V at the coil and coil resistance to pitted contacts and voltage drop under load.
How to Test a Run Capacitor: Meter Method and Under-Load Method
Test HVAC run capacitors two ways, with the meter's capacitance setting and under load with amps × 2652 ÷ volts, and know when to replace one.
Oversized AC: The Symptoms, Why It Happens and What to Do
How to recognize an oversized air conditioner, why it hurts humidity control and equipment life, and the options short of replacing it.