One of the things that tie nearly all residences, commercial buildings, and industrial facilities together is the presence of a heating, ventilation, and air conditioning (HVAC) system. The most prominent visible feature of the HVAC system, and the one most susceptible to direct physical damage, is the air conditioning condenser.

AC Condenser Units

The condenser is a component of the refrigeration cycle that is used to cool the air in a building. Hot high pressure refrigerant gas is pumped from a compressor to the outdoor condenser, where it loses the heat to the outside. The condenser removes the heat from the system by using a fan to pull air across a coil that the refrigerant runs through. In order to remove that heat with maximal efficiency, the condensing unit typically features a coil made of copper (high thermal conductivity) that is covered with many thin aluminum fins (high surface area). Condensers are installed in areas that are exposed to outside air, such as rooftops or ground pads.

How Are Condenser Units Damaged by Hail?

In order to function efficiently, AC condenser units must be exposed to outside air.  This also means that they are exposed to the hazards of the outdoors, including impact by hailstones. The National Weather Service (NWS) records indicate that from 2010 to 2013, the US experienced an average of nearly 7,000 hail reports per year1. This figure only accounts for hailstones measuring more than 1 inch in size, which can be considered the threshold for damaging hail.

When an AC condensing unit is struck by hailstones, it can cause damage by denting and deforming the thin aluminum fins that cover the coil. These fins are spaced close together, and when they are deformed, they can press together or bend back against the copper coil. These types of damage will block air flow in that section of the coil.

If enough of the coil is blocked, and the fan cannot pull enough air through the fins, the condenser will not function efficiently. This will result in increased running time for the AC system, inadequate cooling, and a shortened lifespan for the compressor and other mechanical components.

Homeowners and businesses will typically report this damage as “not enough cooling” or indicate that “the AC is running nonstop.” By the time a claim is made, they may already have a contractor offering to solve the problem by replacing the whole condenser unit.

A note about hail protection: Many residential and commercial condensers offer hail guards to protect the coils from damage. These can consist of wire screens or even sheet metal armor. The more robust the protection, the less likely that the unit will suffer hail damage, but too much protection can block airflow and lead to inefficient operation.

Repair or Replace?

When a condenser unit is damaged by hail, it can often be restored to its pre-loss condition by “combing” the fins with a special tool. A fin comb has thin plastic or metal teeth that fit between the aluminum fins of the condenser coil. Because the fins are thin and malleable, a technician can straighten them by pulling a comb along the coil. This is typically a far more cost-effective method to restore the efficiency of the condenser.

If the deformation of the fins is too extensive, or if large hailstones have caused damage to the copper tubing itself, then it may be necessary to replace the coil. In medium and large commercial or industrial units it can be cost-effective to replace just the coil, without the increased costs of a full replacement condenser.

The cost advantage of combing out the hail damage can be substantial in some cases. Combing involves a few hours of labor, and does not require the purchase f any materials; replacing a coil or an entire condenser unit requires installation labor, thousands of dollars worth of materials, and even crane rental fees for rooftop units.

Questions Amset Will Answer about HVAC Hail Damage

In evaluating a hail damage claim, Amset will seek to answer the following questions:

  • Was there a hailstorm in the area?
  • Does an inspection reveal any damage to the HVAC units?
  • What level of repair (if any) is warranted based on the severity of the damage?
  • What is a fair and reasonable cost to perform the necessary repairs?

Amset has investigated hail damage claims involving as many as 1,000 units at commercial/industrial facilities, shopping malls, college campuses, and apartment complexes throughout the US.  We have produced cost savings by identifying the damage to each individual unit so that repairs can be performed in an efficient and cost-effective manner.


1. “Annual Severe Weather Report Summary – 2013.” Storm Prediction Center Annual Report. NOAA/National Weather Service.