18
COMPRESSOR
ACCUMULATOR
OUTDOOR COIL
INDOOR COIL
LCS
LEGEND
HPS – High Pressure Switch
LCS – Loss of Charge Switch
Accurater
®
Metering De vice
Arrow indicates direction of flo w
TXV in Metering
Position
Bypass
Position
HP S
C03011
Fig. 22 -- Typical Heat Pump Operation, Cooling Mode
Step 2 — Start--Up Adjustments
Complete the required procedures given in the Pre--Start--Up
section before starting the unit. Do not jumper any safety devices
when operating the unit. Do not operate the unit in Cooling mode
when the outdoor temperature is below 40
_
F (4
_
C) (unless
accessory low--ambient kit is installed). Do not rapid--cycle the
compressor. Allow 5 min. between “on” cycles to prevent
compressor damage.
CHECKING COOLING AND HEATING CONTROL
OPERATION
Start and check the unit for proper control operation as follows:
1. Place room thermostat SYSTEM switch or MODE control
in OFF position. Observe that blower motor starts when
FAN mode is placed in FAN ON position and shuts down
within 60 sec (030--060 size) or 30 sec (024 size) when
FAN MODE switch is placed in AUTO position.
2. 2. Place system switch or MODE control in HEAT
position. Set control above room temperature. Observe
that compressor, outdoor fan, and indoor blower motors
start. Observe that heating cycle shuts down when control
setting is satisfied.
3. 3. When using an automatic changeover room thermostat,
place both SYSTEM or MODE control and FAN mode
switches in AUTO positions. Observe that unit operates in
Cooling mode when temperature control is set to “call for
Cooling” (below room temperature), and unit operates in
Heating mode when temperature control is set to “call for
Heating” (above room temperature).
IMPORTANT
: Three--phase, scroll compressors are direction
oriented. Unit must be checked to ensure proper compressor
3--phase power lead orientation. If not corrected within 5 minutes,
the internal protector will shut off the compressor. The 3--phase
power leads to the unit must be reversed to correct rotation. When
turning backwards, the difference between compressor suction
and discharge pressures may be near zero.
CHECKING AND ADJUSTING REFRIGERANT
CHARGE
The refrigerant system is fully charged with R--410A refrigerant
and is tested and factory sealed.
NOTE
: Adjustment of the refrigerant charge is not required
unless the unit is suspected of not having the proper R--410A
charge. The charging label and the tables shown refer to system
temperatures and pressures in Cooling mode, only. A refrigerant
charging label is attached to the outside of the service access door.
If charge level is suspect in Heating mode, reclaim all refrigerant
and charge to nameplate amount. (This information may be
obtained from the physical data table also.) The charging label
and the tables shown refer to system temperatures and pressures
in Cooling mode only. A refrigerant charging label is attached to
the outside of the service access door. If charge level is suspect in
Heating mode, reclaim all refrigerant and charge to nameplate
amount. (This information may be obtained from the physical
data table also.)
IMPORTANT
: When evaluating the refrigerant charge, an
indicated adjustment to the specified factory charge must always
be very minimal. If a substantial adjustment is indicated, an
abnormal condition exists somewhere in the cooling system, such
as insufficient airflow across either coil or both coils.
REFRIGERANT CHARGE
The amount of refrigerant charge is listed on the unit nameplate
and/or the physical data table. Refer to the Refrigeration Service
Techniques Manual, Refrigerants Section.
NO CHARGE
Check for leak. Use standard evacuating techniques. After
evacuating system, weigh in the specified amount of refrigerant
(refer to system data plate).
604D
