What Happens When Your Furnace and Air Conditioner Don’t Get Enough Air?

Ample air flow is critically important to the health and well-being of your HVAC units. Preventative maintenance helps ensure that your equipment gets the air that it needs to function properly.

Many Nashville residents and business owners do not realize their heating and air conditioning system operates approximately 3300 hours per year. To put this “run time” in perspective, a car driven for the same 3300 hours at 65 miles per hour would travel 214,500 miles! No one would consider such a journey without arranging for oil changes, lubrication, and routine tune-ups along the way to ensure the efficiency, safety, and reliability of the vehicle.

Your home heating and air conditioning system serves you many more hours than your car, and, like your car, needs routine tune-ups. This is not just a case of “pay me now or pay me later.” It is a case of “pay me now or pay me considerably more, later.”

Your best insurance against HVAC failure and cost containment is equipment preventative maintenance.

Air conditioning equipment is designed to operate with a specific quantity of air passing over its indoor coil surface. When air filters are not replaced, they clog and become coated with dirt. Similarly, the indoor coils get coated with dirt. This dirt reduces the amount of air through the unit below the design limit, leading to catastrophic failure.

What Happens if There’s Not Enough Air in the Cooling Mode?

When this happens, the coil temperature drops. When it drops below the freezing point, ice forms on the coil, which further reduces the airflow, and reduces the coil temperature.

The compressor within the unit is a pump, which is designed to pump a vapor. As the airflow through the indoor coil drops, there isn’t enough heat being removed from the air passing over the coil to vaporize the liquid refrigerant inside the coil. Thus, instead of receiving a vapor, the compressor receives liquid refrigerant.

This is called “liquid slugging.” As liquids are not compressible, cylinder pressure exceeds the design limits and the valves, connecting rods, pistons, or other internal components are destroyed. The air conditioning unit starts out requiring that its filters need to be replaced, next it needs a new compressor -- which is a significantly more costly repair!

So, affordable preventative maintenance or a costly new compressor? The choice is yours.

What Happens if There’s Not Enough Air in the Heating Mode?

Low airflow causes the heat exchanger to overheat. Heat exchangers are designed to operate at temperatures between 120 degrees Fahrenheit and 200 degrees. At higher temperatures, the heat exchanger oxidizes, its lifespan is reduced, or it cracks and breaks.

Air conditioning equipment is designed to operate with a specific quantity of air passing over its indoor coil surface. When air filters are not replaced, they clog and become coated with dirt. Similarly, the indoor coils get coated with dirt. This dirt reduces the amount of air through the unit below the design limit, leading to catastrophic failure.

What Happens if There are Loose or Broken HVAC Drive Belts?

Once again, airflow through the equipment is reduced below design limits. Additionally, loose drive belts slip on the pulleys. This wears a groove in the pulley so that when the belt is replaced, the new belt is ruined in a shorter period of time by the worn pulleys.

What Happens if There Outdoor Coils are Dirty?

When this happens the ability of these coils to transfer heat is reduced and the airflow through the condenser coil is reduced (blocked by dirt and dust.) When the ability to transfer heat is reduced, the operating temperatures and pressures of the air conditioning unit increase. A unit designed to operate at ambient temperatures of 115 degrees or more, may stop operating an outdoor temperature of 90. Due to the reduced heat transfer capability, the operating temperatures and pressures within the unit exceed the manufacturer’s safe limit and the unit shuts down.

If the unit does not exceed the manufacturer’s limits by enough to shut down, it will continue to run at reduced capacity and efficiency, and at an increased rate of wear and energy consumption due to the increased workload.

The strongest arguments for preventative maintenance include reducing wear, minimizing energy costs, and preventing catastrophic failure. Contact TBT HVAC to arrange for preventative maintenance.

TBT HVAC