What is happening at home?
What is happening with your heating or cooling?
Choose the closest symptom. You do not need to know the equipment name or technical term.
Gas smell, carbon-monoxide alarm, smoke, or sparking?
Leave the area and follow the safety instructions before troubleshooting.
Common symptoms
Start with what you notice
These are common starting points. Each page separates safe homeowner checks from work that belongs to an HVAC professional.
Choose your system
Browse HVAC problems by category
Pick the equipment or comfort issue that is closest. The category pages include every approved problem guide in that group.
Whole-system behaviorStart here when the entire heating or cooling system has stopped, a breaker keeps tripping, or the equipment changed after a storm or power outage.
Air conditioningChoose the AC symptom you can see or feel, such as warm air, weak cooling, water, ice, noise, or a unit that will not start.
Furnaces and heatingFind the closest no-heat, cold-air, ignition, cycling, noise, odor, or leak symptom.
Heat pumpsHeat pumps use the same outdoor system for heating and cooling, so the season and operating mode matter.
Ductless mini-splitsChoose what the wall-mounted unit or outdoor unit is doing.Boilers and radiatorsFind guidance for no heat, no hot water, lockouts, pressure changes, leaks, noises, frozen condensate, and radiators that stay cold.
Airflow, ductwork, and comfortStart with the comfort pattern: weak or missing airflow, one room that behaves differently, an upstairs that stays hot, noisy ducts, condensation, dust, or filters that clog unusually fast.
Thermostats, zoning, and controlsChoose a blank screen, an unresponsive thermostat, a wrong temperature reading, changing settings, a Wi-Fi problem, or a zone that will not heat or cool.
Humidity, air quality, and ventilationFind the closest humidity, ventilation, odor, dust, humidifier, dehumidifier, or purifier symptom.
Safety and urgent conditionsGas odors, carbon-monoxide alarms, smoke, sparks, electrical burning smells, and unusual furnace flame or soot require a safety-first response.Browse by what you notice
You can start without knowing the system
Choose an observation and the finder will ask only what changes the service, urgency, or safety instruction.
Not sure what you need?
Tell us what your home is doing
You do not need to know the HVAC term. Choose the closest issue and we will show you the best next step.
More problems
Expert Guides
Planning, maintenance, and system education
Use Problems for an active symptom. Use Expert Guides when you are comparing options or learning how your system works.
SavingsIs a Smart Thermostat Worth It? An Honest Look at the Savings
Smart thermostats can save money, but not for every home. Here’s how to tell if the payoff is real or just marketing.
Read guide
MaintenanceWhy Your Thermostat Reads Wrong, and Where It Should Actually Be
A badly placed thermostat can make a healthy HVAC system run wrong. Here is how to tell location problems from sensor failure.
Read guide
HeatingWhy One Radiator Is Cold When the Rest Are Hot
A step-by-step guide to why one radiator stays cold, what you can safely check, and what should be left to a heating pro.
Read guideNeed HVAC Help Now?
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