Checking & Adjusting Refrigerant Charge; Indoor Airflow And Airflow Adjustments - Carrier Performance 48VR-A Installation Instructions Manual

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 will be minimal.
Checking and Adjusting Refrigerant Charge
The refrigerant system is fully charged with PuronR (R- -410A)
refrigerant and is tested and factory sealed. Allow system to operate
a minimum of 15 minutes before checking or adjusting charge.
NOTE: Adjustment of the refrigerant charge is not required unless
the unit is suspected of not having the proper PuronR (R- -410A)
charge.
A subcooling chart is attached to the inside of the compressor
access panel. (See Table 9 and Fig. 20.) The chart includes the
required liquid line temperature at given discharge line pressures
and outdoor ambient temperatures for high stage cooling.
An accurate thermocouple- - or thermistor- -type thermometer, and a
gauge manifold are required when using the subcooling charging
method for evaluating the unit charge. Do not use mercury or small
dial- -type thermometers because they are not adequate for this type
of measurement.
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit damage.
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.
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.
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 gauge hoses to low- - and high- -pressure
service fittings, respectively.
3. Start unit in high stage cooling mode and let unit run until
system pressures stabilize.
4. Measure and record the following:
a. Outdoor ambient- -air temperature (F [C] db).
b. Liquid line temperature (F [C]).
c. Discharge (high- -side) pressure (psig).
d. Suction (low- -side) pressure (psig) (for reference only).
5. Using "Subcooling Charging Charts," compare outdoor- -air
temperature(F [C] db) with the discharge line pressure
(psig) to determine desired system operating liquid line
temperature (See Table 9).
6. Compare actual liquid line temperature with desired liquid
line temperature. Using a tolerance of  2F (1.1C), add
refrigerant if actual temperature is more than 2F (1.1C)
higher than proper liquid line temperature, or remove
refrigerant if actual temperature is more than 2F (1.1C)
lower than required liquid line temperature.
NOTE:
If the problem causing the inaccurate readings is a
refrigerant leak, refer to the Check for Refrigerant Leaks section.

Indoor Airflow and Airflow Adjustments

CAUTION
!
UNIT OPERATION HAZARD
Failure to follow this caution may result in unit damage.
For cooling operation, the recommended airflow is 350 to
450 cfm for each 12,000 Btuh of rated cooling capacity. For
heating operation, the airflow must produce a temperature
rise that falls within the range stamped on the unit rating
plate.
NOTE: Be sure that all supply- -and return- -air grilles are open,
free from obstructions, and adjusted properly.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Disconnect electrical power to the unit and install lockout
tag before changing blower speed(s).
This unit has independent fan speeds for low stage cooling and
high stage cooling. In addition, units have the field- -selectable
capability to run an enhanced dehumidification ('DHUM') speed
on high stage cooling (as low as 320CFM per ton). Coupled with
the improved dehumidification associated with low stage cooling,
the DHUM speed allows for a complete dehumidification solution
independent of cooling stage. Units also have independent fan
speeds for low stage gas heating and high stage gas heating. Table
7 shows the operation modes and the associated fan speeds with
each mode:
Table 7 – Operation Modes and Fan Speeds
208/230 VAC Models
OPERATION MODE
Low Stage Gas Heating
High Stage Gas Heating
Low Stage Cooling/Heat Pump
High Stage Cooling/Heat Pump
High Stage Enhanced
Dehumidification Cooling
Continuous Fan
The evaporator fan motor is factory set to provide 5 different fan
speeds to choose from for the various operation modes. Models are
factory- -shipped with 4 speed wires connected with one spare
speed wire available.
28
FAN SPEED TAP
CONNECTION
LO HEAT
HI HEAT
LO COOL
HI COOL
DHUM
LO COOL