Common HVAC Problems

A guide to identifying common issues with residential heating and cooling systems.

The furnace starts and the burners light up, but they only stay on for a few seconds before shutting off.
The inducer motor runs and the igniter glows bright orange, but the burners never light.
The inducer motor starts spinning, but the igniter never glows orange.
The furnace fan stays on constantly and will not turn off.
The inducer motor is making unusual noises.
The furnace repeatedly trips the circuit breaker whenever it tries to start.
The furnace does not respond at all when the thermostat is adjusted.

The indoor evaporator coil freezes into a block of ice, and the copper line outside is covered in ice.
The system runs continuously but provides no cooling, blowing only room-temperature air.
The outdoor compressor is running and making noise, but the fan on top is not spinning.
The AC circuit breaker trips instantly every time the cooling is turned on.
The outdoor unit is not receiving 24V power when the thermostat calls for cooling.
The furnace (heating) runs simultaneously with the AC (cooling).
The compressor fails to start, often making a humming sound before stopping.

The outdoor unit is encased in thick ice or trips the breaker during defrost.
The system blows cold air in winter or hot air in summer (Reversing valve issue).
The air coming from the vents is only lukewarm or not hot enough.
The outdoor unit never turns on, or it continues running even when the system is off.
The indoor unit runs but no air comes out, or the breaker trips (especially in Emergency Heat).
The thermostat is blank and the entire system has lost power.

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