Allied Air Enterprises 4HP16LT - Manual (Page 13)

506468-01 Issue 1004 Page 13
Cooling Cycle
Use gauge ports on suction line valve and liquid line valve for evacuating refrigerant lines and indoor coil. Use
suction gauge port to measure suction pressure during charging.
Figure 12
OUTDOOR COIL
DEFROST THERMOSTAT
EXPANSION/CHECK VALVE
BIFLOW
FILTER / DRIER
TO
R410A
DRUM
LOW
PRESSURE
HIGH
PRESSURE
COMPRESSOR
REVERSING VALVE
SUCTION
LINE
VALVE
MUFFLER
NOTE - ARROWS INDICATE
DIRECTION OF
REFRIGERANT FLOW
SUCTION
SERVICE
PORT
EXPANSION/CHECK VALVE
INDOOR UNIT
OUTDOOR UNIT
LIQUID
LINE
SERVICE
PORT
GAUGE MANIFOLD
DISTRIBUTOR
INDOOR
COIL
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve
2. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of R410A.
3. If room temperature is below 70°F, set the room thermo-
stat to call for heat. This will create the necessary load
for properly charging the system in the cooling cycle.
4. Use a digital thermometer to record the outdoor
ambient temperature.
5. When the heating demand has been satisfied, switch
the thermostat to cooling mode with a set point of 68°F.
When pressures have stabilized, use a digital thermom-
eter to record the liquid and suction line temperatures.
6. The outdoor temperature will determine which charg-
ing method to use. Proceed with the appropriate
charging method.
Charge Using Weigh-In Method
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, first locate and repair any leaks then
use the weigh-in method to charge the unit.
1. Recover the refrigerant from the unit.
2. Conduct a leak check, then evacuate as previously
outlined.
3. Weigh in the charge according to the total amount
shown on the unit nameplate.
If weighing facilities are not available, use one of the
following procedures to charge the unit.
Charge Using Subcooling Method –
Outdoor Temperatures Below 65°F
When the outdoor ambient temperature is below 65°F, the
subcooling method can be used to charge the unit. It may
be necessary to restrict the air flow through the outdoor
coil to achieve pressures in the 200-250 psig range.
These higher pressures are necessary for checking the
charge. Block equal sections of air intake panels and
move obstructions sideways until the liquid pressure is in
the 200-250 psig range (see Figure 13 on page 14).
1. With the manifold gauge hose still on the liquid
service port and the unit operating stably, use a digital
thermometer to check the liquid line temperature. For
best results, use the same digital thermometer to
check both the outdoor ambient and the liquid line
temperatures.
2. At the same time, record the liquid line pressure reading.
3. Use the temperature/pressure chart (Table 5 on page 14)
to determine the saturation temperature for the liquid line
pressure reading.