2
surrounding air (even outside air at ex-
tremely cold temperatures), and ends
with the indoor coil releasing or reject-
ing heat to the air around it.
Variable refrigeration circuit-
ing (VRC) — 38AQS units
For that extra measure of heat pump
performance, variable refrigeration cir-
cuiting provides improved heat trans-
fer. The design combines check valves
and fixed-bore refrigerant metering to
optimize the circuiting of the outdoor
coil. This circuiting achieves the best
performance possible during both the
heating and cooling modes. The VRC
feature provides three valuable benefits
that ordinary heat pump systems can-
not match:
• Improved heat transfer, resulting in
a higher Coefficient of Performance
(COP), especially at temperatures
below 47 F.
• Improved reliability, by ensuring the
proper quality of refrigerant is flow-
ing to the compressor.
• Faster coil defrosting.
38AQS application versatility
Whether for a new application or
replacement, these Carrier split system
heat pumps offer time-proven perfor-
mance for year-round comfort in any
climate.
Rugged long life compressor
— 38AQS units
Model 38AQS outdoor sections are
equipped with 06D semi-hermetic
compressors, which are famous
throughout the industry for their reli-
ability. These compressors have vane-
type oil pumps with positive oil pres-
sure, an oil pressure regulating valve,
class F stator windings, capacity reduc-
tion, oil level sight glass, and service
valves. Through cylinder unloading,
the 38AQS012 and 016 (one electric
unloader is standard) can reduce capac-
ity during the cooling phase to reduce
energy usage and improve space tem-
perature regulation. A Cycle-LOC™
device in the 38AQS control box holds
the compressor off-line if any opera-
tional or safety device trips the com-
pressor. The unit can be reset manually
at the thermostat.
Features to consider,
38AQS008 units
Controls for performance effi-
ciency —
The 38AQS008 unit offers
the building owner operating controls
and components designed for perfor-
mance dependability. The highly effi-
cient semi-hermetic compressor is en-
gineered for long life and durability.
The compressor includes overload pro-
tection and compressor vibration isola-
tion for further enhancement of quiet
operation. The high-pressure switch
protects the entire refrigeration system
from abnormally high operating pres-
sures. A loss-of-charge switch is also
provided to protect the system against
low charge conditions.
The unit also includes anti-short-
cycling protection which protects the
compressor from the damage that can
be caused by rapid compressor cycling.
The 24-v control circuit transformer
permits quick, easy wiring of standard
and programmable 24-v thermostats.
Latest safety standards for
38AQS008 units are assured through
UL (Underwriters’ Laboratories) and
UL, Canada approval.
The 38AQS008 utilizes a state-of-
the-art defrost board with field config-
urable timed defrost cycles. The defrost
board may be easily configured for de-
frost cycles of 30, 50, or 90 minutes,
depending upon the application.
Features to consider,
38AQS012,016 units
A low oil pressure switch protects
against loss of oil pressure. The
Chronotemp™ defrost system allows
defrost to occur every 60 minutes if the
defrost thermostat is calling for defrost-
ing. If the thermostat is not calling for
defrosting, another 60 minutes must
pass before defrosting begins.
Motor failure due to electrical over-
load is prevented by temperature and
current sensors. Coil quality and per-
formance are enhanced by copper
tubes and aluminum fins, which pro-
vide maximum heat transfer. The
coil is circuited for subcooling. A large
heat transfer surface offers additional
efficiency.
Heat pump performance
enhanced by variable refriger-
ation circuiting —38AQS units
Cooling mode —
During cooling, the
38AQS outdoor coil condenses the hot
gas through a converging series circuit.
First the check valve system feeds all
the hot gas through the circuits at the
bottom half of the coil. This desuper-
heats and partially condenses the hot
gas. The hot gas is then routed
through the upper half of the coil and
finally through the subcooling coil. The
subcooled liquid then enters the liquid
line. This process also occurs during
defrosting, resulting in improved, more
thorough defrosting by assuring that
the bottom half of the coils is hot and
clear so that frost slides down and off.
Heating mode —
During heating,
the 38AQS outdoor coil becomes the
evaporator, absorbing available heat
from the outdoor air. The check valve
system directs the flow of liquid refrig-
erant to individual parallel circuits, cre-
ating a “full face” active condition; the
entire coil face is exposed to the same
temperature of entering refrigerant.
The result is maximum recovery of
heat from outdoor air, a higher COP,
and improved reliability.
Innovative Carrier 40RMQ
indoor units are custom
matched to 38AQS outdoor
units for superior system
performance
The 40RMQ Series has excellent fan
performance, efficient direct-
expansion (DX) coils, easy installation,
and a unique combination of indoor air
quality features. Its versatility and state-
of-the-art features help to ensure that
your heat pump system provides eco-
nomical performance now and in the
future.
06D COMPRESSOR
