HVAC System Does Not Stay on Long Enough

Part of owning a home is dealing with regular troubleshooting and maintenance to keep the appliances such as your HVAC system smoothly running. Whether you are working with the heating or cooling side of an HVAC system, if it’s not staying on long enough to sufficiently heat or cool your home, the underlying issues need to be fixed so you can get back to enjoying your living conditions, rather than sweating or freezing.

Broken Thermostat

A properly functioning HVAC unit heats and cools the home throughout the year.

A dirty thermostat can affect both the heating and cooling sides of an HVAC system. To start, remove the cover plate on the main thermostat for the home and ensure the interior is free of debris, in the case of physical thermostats that have a slider. For digital thermostats, ensure the interior is free of dust and all the leads are connected. Disconnect the HVAC system from its power source, or turn off the breaker, and give it a couple of minutes before turning it back on to reset the system. Adjust the thermostat to the desired temperature. If this doesn’t work, call a technician to replace the thermostat.

Pilot Light

For the heating side of an HVAC unit, the furnace relies on a pilot light to light the burner and heat the home. Over time, the pilot light tip becomes clogged with dirt, debris and soot. A toothbrush is the perfect cleaning tool to bring the pilot light’s tip back to functioning condition so the gas flows freely. Make sure the furnace is off while you are cleaning it.

Coolant Leak

An air conditioning unit relies on a gas coolant to produce the cool air that flows through the home. HVAC units are designed to last a lifetime without ever needing to refill the coolant. However, leaks can occur naturally over time at connection points, and human error during installation can cause damage, which causes leaks. If the AC unit won’t stay on to cool the home, you may have a coolant leak. Look for ice buildup within the unit on the condenser coils and gas lines, and call a technician to fix the issue if there are leaks, and to refill the reservoir.

Mechanical Issues

HVAC units rely on a variety of mechanic aspects to keep the machine running, both on the heating and cooling side of things. For example, the ignition switch that is meant to ignite the pilot light might fail to light, leading to a furnace kicking on, running for a short period of time, then shutting off when the furnace realizes it isn’t pushing out hot air. The blower motor might wear out over time and stop functioning properly, thus turning off too soon. If there is a coolant leak, the system may run for a short period of time then shut off, or the blower might keep blowing while the actual cooling unit has shut down. All mechanical issues must be resolved by a licensed technician to preserve the warranty of the HVAC system.


Restricted airflow can cause an HVAC unit to prematurely shut down. Both the furnace and air conditioning units need airflow to function properly, and filters on the outside of the machine protect the inner workings of the machine. These need to be regularly cleaned to keep airflow to a maximum, or the machine may shut off mid-cycle to avoid overheating. Vacuum the filters every few months to keep them in proper working condition.

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