Carrier PA4G, Installation Instructions Manual

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PA4G: Installation Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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attached to the inside of the compressor access panel. (See Fig. 18
Subcool chart for units with TXV and superheat chart for units with
fixed orifice.) The chart includes the required liquid line temperature at
given discharge line pressures and outdoor ambient temperatures.
A superheat chart is attached to the inside of the compressor access panel
for the unit with fixed metering device. Refer to the charging procedure
on the label.
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.
NOTE: Allow system to operate for a minimum of 15 minutes before
checking or adjusting refrigerant charge.
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 and let 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]) at TXV.
c. Discharge (high-side) pressure (psig).
d. Suction (low-side) pressure (psig) (for reference only).
5. Using Cooling Charging Charts compare outdoor-air temperature
(°F [°C] db) with the discharge line pressure (psig) to determine
desired system operating liquid line temperature (See Fig. 18 ).
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 Check for Refrigerant Leaks section.
Indoor Airflow and Airflow Adjustments
NOTE: Be sure that all supply-and return-air grilles are open, free from
obstructions, and adjusted properly.
This unit is factory-set up for use with a single cooling fan speed. In
addition, this unit has the field-selectable capability to run two different
cooling fan speeds: The rated cooling fan speed (350~400 CFM/Ton)
and an enhanced dehumidification fan speed (As low as 320 CFM/Ton)
for use with either a dehumidistat or a thermostat that supports
dehumidification.
The cooling speed is marked “LOW” on the interface fan board (IFB)
(See Fig. 11 ). The factory-shipped settings are noted in Table 4 . There
are 4 additional speed tap wires available for use in either electric
heating or cooling (For color coding on the indoor fan motor leads, see
Table 3 ). The additional 4 speed tap wires are shipped loose with vinyl
caps and are located in the control box, near the interface fan board
(IFB) (See Fig. 11 ).
Single Cooling Fan Speed Set-up (Dehumidification
feature not used)
To change cooling speed:
1. Remove the vinyl cap off of the desired speed tap wire (Refer to
Table 3 for color coding). Add the wet coil pressure drop in Table 5
to the system static to determine the correct cooling airflow speed
in Table that will deliver the nominal cooling airflow as listed in
Table for each size.
2. Remove the current speed tap wire from the “LOW” terminal on the
interface fan board (IFB) (See Fig. 11 ) and place vinyl cap over the
connector on the wire.
3. Connect the desired speed tap wire to the “LOW” terminal on the
interface fan board (IFB).
NOTE: If accessory electric heat is installed, and the electric heat fan
speed is chosen to be the same as the normal cooling fan speed, the dry
airflow must meet or exceed the minimum airflow speed specified in
Table 2 for the specific size unit.
Two Cooling Fan Speeds Set-up (Dehumidification
feature used)
IMPORTANT: Dehumidification control must open control circuit on
humidity rise above set point.
Use of the dehumidification cooling fan speed requires use of either a 24
VAC dehumidistat or a thermostat which includes control of a 24 VAC
dehumidistat connection. In either case, the dehumidification control
must open the control circuit on humidity rise above the
dehumidification set point.
1. Using Fig. 11 , move the two pin DEHUM jumper from the “STD”
position to the “DEHUM” position.
2. Remove fan speed tap wire from the “LOW” terminal on the
interface fan board (IFB) (See Fig. 11 ).
3. Determine correct normal cooling fan speed for unit and
application. Add the wet coil pressure drop in Table 5 to the system
static to determine the correct cooling airflow speed in Table 5 that
will deliver the nominal cooling airflow as listed in Table 1 for each
size.
NOTE: If accessory electric heat is installed, the dry airflow must meet
or exceed the minimum airflow speed specified in Table 2 for the
specific size unit. The electric heat fan speed will be the same as the
normal cooling fan speed.
4. Remove the vinyl cap off of the desired speed tap wire (Refer to
Table 3 for color coding) for the normal cooling fan speed and place
desired speed tap wire on “HIGH” on the interface board.
5. Refer to airflow tables ( Table 4 - Table 6 ) to determine allowable
speeds for the dehumidification cooling fan speed. In Table 4 ,
speeds that are not allowed for dehumidification cooling are
shaded.
6. Remove the vinyl cap off of the desired speed tap wire (Refer to
Table 3 for color coding) for the dehumidification cooling fan speed
and place desired speed tap wire on the “LOW” connection on the
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.
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.