Carrier 48KH - Manual (Page 16)

Cooling Section Start-Up and Adjustments
C.\trnON: Compiete P5<;«ired procedures
^■vcn mUait ?teparaiìoiì seciioa befx-vres£ar«iig
Do oci jomper asy safetj' devices uhen
operaisog unit.
Do not operate coiiipressoif when oaidoos
iwapecsaote is feeiow 55 F tsm^kr-piiase oniis)
or 40 F
0-ph&s& anksX
Do not perom eompre-ssor to rapid cycle,
ASos?? 5 inisKios i^iwceo o>icies to prevent com-
CHECKING COOLING CONTROL OPERA­
TION — Start and check unit for proper cooling
control operation as follows:
1. Place room thermostat selector switch in OFF
position. Observe that blower motor starts when
fan switch is placed in ON position and shuts off
when fan switch is placed in AUTO, position.
2. Place selector switch in COOL position and fan
switch in AUTO, position. Set cooling control
below room temperature. Observe that compres­
sor, condenser fan and evaporator blower motors
start. Observe that cooling cycle shuts down
when control setting is satisfied.
3. When using an automatic changeover room
thermostat, place both selector and fan switches
in AUTO, position. Observe that unit operates in
heating mode when temperature control is set to
call for heating (above room temperature) and
operates in cooling mode when temperature con­
trol is set to call for cooling (below room
temperature).
CHECKING AND ADJUSTING REFRIG­
ERANT CHARGE — Refrigerant system is fully
charged with R-22 refrigerant, tested and factory
sealed. For most applieations, factory charge is the
correct amount for best performanee; however, this
charge may require a slight adjustment to attain
rated performance.
NOTE: Adjustment of refrigerant charge is not re­
quired unless unit is suspected of not having proper
R-22 charge. For all applications, correct R-22
charge for best performance is charge that results in
a suction gas superheat of 5 F at compressor inlet
when unit is operating at ARI rating conditions of
95 F db outdoor and 80 F db/67 F wb indoor.
A superheat charging label is attached to outside
of compressor access door. Label includes a Field
Superheat Charging Table and a Required Suction-
Tube (F) temperature chart.
An accurate superheat-, thermocouple-, or
thermistor-type thermometer, a sling psychrometer
and a gage manifold are required when using super­
heat charging method for evaluating unit charge.
Do not use mercury or small dial-type thermometers
because they are not adequate for this type of
measurement.
CAUXXOK; WlieRevalhatiHg charge,
an jeadicaifid adittstajest to specified factory
charge mast almys be ai&nntst ifasabsiartisaJ
adjastraeat £s tiidicated, aa ahtjormal coaditto«
exists s
sufficient airflow across either coil or both coils.
Proceed as follows:
1. Remove caps from low- and high-pressure service
fittings.
2. Using hoses with valve core depressors, attach
low- and high-pressure gage hoses to low- and
high-pressure service fittings, respectively.
3. Start unit in cooling mode and let unit run until
system pressures stabilize.
4. Measure and record the following:
a. Outdoor ambient-air temperature (F db).
b. Evaporator inlet-air temperature (F wb).
c. Suction-tube temperature (F) at low-side
service fitting.
d. Suction (low-side) pressure (psig).
5. Using Field Superheat Charging Table, compare
outdoor-air temperature (F db) with evaporator
inlet-air temperature (F wb) to determine desired
system operating superheat temperature.
6. Using Required Suction-Tube(F) table, compare
desired superheat temperature with suction (low-
side) operating pressure (psig) to determine
proper suction tube temperature.
7. Compare actual suction-tube temperature with
proper suction tube temperature. Using a tol-
eranceof ± 5 F, add refrigerant if actual tempera­
ture is more than 5 F higher than proper suction
tube temperature, or remove refrigerant if actual
temperature is more than 5 F lower than required
suction-tube temperature.
•NOTE: If the problem causing inaccurate readings is
a refrigerant leak, see Unit Preparation, Refrig­
erant Leaks section of these instructions.
INDOOR AIRFLOW AND ADJUSTMENTS
CAUTiON: ForcobJitig, recomtneaded airflow
is 35b to 45bcfta for eacht 12,0@8 Btoh oT rated
cooliKgcapadty, ForlieatÈs^, airflow Kttisi pro-
dace a temperatore rise that taife vrfthm the
raijge taaisrped on aail piate,
Models48KH,KL end-discharge units have direct-
drive blower motors. All motors are factory-
connected to deliver proper heating and cooling air­
flows at normal external static pressures (except for
some 208-v applications).
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