In the summer months, when severe weather is most prevalent, property carriers see an increase in
claims for lightning damage to HVAC
equipment, and most often to the
compressor. While lightning damage
does frequently occur this time of
year, HVAC compressor damage due to
lightning is commonly misdiagnosed.
More often than not, an HVAC claim
that is originally reported as damaged
by lightning is ultimately found to have
suffered damage due to some other
cause of loss.
No matter the time of year, one of
the most common culprits of compressor failure is mechanical damage due to
age-related wear and tear. In fact, nearly
43% of all compressors (regardless of how
the damage is initially reported) fail due
to this cause of loss.
HVAC compressor function
Regardless of application (refrigera-
tion or HVAC) or building type (res-
idential or commercial), the primary
purpose of a compressor is to draw
low-pressure refrigerant vapor from
the evaporator, compress that vapor,
and prepare the refrigerant for heat
removal in the condenser. Residential
compressors typically operate on sin-
gle phase alternating current (AC),
and thus require a capacitor to assist
in both starting and running the com-
pressor while energized.
Considered the “heart” of the HVAC
system, the compressor is not only critical to proper system function, but can
often be impossible to repair and expensive to replace. Moreover, without understanding the root cause of compressor failure, the simple act of replacing
this component may not ultimately resolve the overarching issue. When handling HVAC claims, it is critical to understand what caused the compressor to
fail before agreeing on a scope of repair
for settlement.
Mechanical damages
A major cause of damage to a compressor
is mechanical failure, and a major contributing factor is a lack of system maintenance, such as not changing the indoor
air filters or allowing dirt and debris to
build up on the outdoor condenser or
indoor evaporator coils. Such negligence
can lead to excessive stress on the compressor, and may cause it to overheat and
“burn out” prematurely.
Another reason for mechanical failure
is improperly sized equipment or failure
to follow system repair best practices.
An oversized metering device (com-
monly called a Thermostatic Expan-
sion Device or TXV) at the evaporator
coil may allow more refrigerant to enter
the evaporator than can be vaporized,
causing a floodback of refrigerant to the
compressor, wearing out the compres-
sor’s bearing surfaces and accelerating
its failure.
If the refrigeration line is breached
(intentionally or as a result of a leak),
great care must be taken in performing
system repairs. If the filter-drier is
not replaced, and proper steps are
not taken to evacuate and purge the
refrigeration system, moisture or
contaminants may create acid in the
system, possibly leading to premature
compressor failure.
Electrical damages – shorted
and open windings
Like traditional single-phase motors,
single-phase compressors contain both
“start” and “run” windings, which are
a series of copper wires wound around
the stator, and which cause the motor to
turn when energized by electricity. As the
names imply, the start winding is engaged
HVAC Compressor Damage:
Lightning or Wear & Tear?
Dirty evaporator coil. (Photo: HVACi)
