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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.
WARNING
!
EXPLOSION HAZARD
Failure to follow this warning could
result in death, serious personal injury,
and/or property damage.
Never use air or gases containing
oxygen for leak testing or operating
refrigerant compressors.
mixtures of air or gases containing
oxygen can lead to an explosion.
NOTE: Adjustment of the refrigerant charge is not required unless
the unit is suspected of not having the proper PuronR (R- -410A)
charge.
NOTE:
Some units have fixed orifice refrigerant metering
devices. There is a different charging procedure for both expansion
devices. Refer to the correct procedure for your unit.
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 inside of the compressor access
panel. (See Table 9 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.
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.
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 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 "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 Table 9).
6. Compare actual liquid line temperature with desired liquid
line temperature. Using a tolerance of 2F (1.1C), add
refrigerant if actual temperature is more than 2F (1.1C)
higher than proper liquid line temperature, or remove
refrigerant if actual temperature is more than 2F (1.1C)
lower than required liquid line temperature.
NOTE:
refrigerant leak, refer to the Check for Refrigerant Leaks section.
Indoor Airflow and Airflow Adjustments
Pressurized
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.
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.
This unit has independent fan speeds for gas heating and cooling
modes. Single phase models also have a dedicated continuous fan
speed. All models (1 phase and 3 phase), have a field- -selectable
capability to run two different cooling speeds: A normal cooling
fan speed (350- -450 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.
This unit is factory- -set for use with a single cooling fan speed. For
single phase models, the cooling speed is marked "COOL" on the
IGC (See Fig. 17). For 3- -phase models, the cooling speed is
marked "LOW" on the interface board (IFB)(See Fig. 18). The
factory- -shipped settings are noted in Tables 10 and 11. There are
up to 3 additional speed tap wires available for use in either gas
heating mode, cooling mode, or continuous fan mode (For color
coding on the indoor fan motor leads, see Table 8). For single
phase models, one of the additional speed tap wires is connected to
the continuous fan, with the other 2 wires shipped loose in the
control box near the IGC. For three phase models, the additional 3
speed tap wires are shipped loose with vinyl caps and are located in
the control box near the interface fan board (IFB) (See Fig. 18).
Gas Heating Fan Speed Set- - up (Single Phase Models):
To change the gas heating speed:
1. Remove existing speed tap wire from the "HEAT" terminal
on the IGC.
2. Connect the desired speed tap wire on the "HEAT" terminal
on the IGC board. Make sure that the speed chosen delivers
temperature rise within the rise range listed on the unit.
"High" blower speed is for high static cooling only and
must not be used for gas heating speed.
23
If the problem causing the inaccurate readings is a
CAUTION
!
WARNING
!
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