Indoor Airflow And Airflow Adjustments; Continuous Fan Operation - Bryant LEGACY PURON 704D Series Installation Instructions Manual

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. 16).
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 ADJUST-
MENTS
All 704D blower motors are factory wired for nominal cooling
airflow operation at minimum external static pressure. See Table 1.
NOTE: Be sure that all supply- - and return- -air grilles are open,
free from obstructions, and adjusted properly.
Table 3 – Color Coding for Indoor Fan Motor Leads
Black = High Speed
Orange = Med- -High Speed
Red = Med Speed
Pink = Med- -Low Speed
Blue = Low Speed
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.
The fan speed of the unit is connected to the "HIGH" terminal on
the interface fan board (IFB) (See Fig. 12, 13 14 and 15). The unit
is factory- -shipped with a fan speed as noted in Table 4. There are
4 additional speed tap wires available for use (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 IFB.
To change the fan speed, remove the vinyl cap off of the desired
speed tap wire (Refer to Table 3 for color coding). Remove the
current speed tap wire from the "HIGH" terminal on the interface
fan board (IFB) (Fig. 12) and place vinyl cap over the connector on
the wire. Connect the desired speed tap wire to the "HIGH"
terminal on the IFB. For optimum performance, add the wet coil
pressure drop in Table 5 to the system static to determine the
correct cooling airflow speed in Table 4 that will deliver the
nominal cooling airflow as listed in Table 1 for each size.
NOTE: For cooling operation, the recommended airflow is 350 to
450 CFM for each 12,000 Btuh of rated cooling capacity.
NOTE: If accessory electric heat is installed in the unit, the dry
airflow must meet or exceed the minimum airflow specified in
Table 2 for the specific size. Use Table 4 to determine dry airflow
for a known external static pressure. Electric heat fan speed is the
same as cooling fan speed.

Continuous Fan Operation

The continuous fan operates at the same fan speed as cooling
operation.
Fig. 12 - - Interface Fan Board (IFB)
12
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