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Fig. 27 — Forced Circulation Method
For average scale deposit, allow solution to remain in condenser
overnight. For heavy scale deposit, allow 24 hours. Drain con-
denser and flush with clean water. Follow acid manufacturer’s
instructions.
Checking System Charge
Units are shipped with full operating charge. If recharging is nec-
essary:
1. Insert thermometer bulb in insulating rubber sleeve on liquid
line near filter drier. Use a digital thermometer for all tem-
perature measurements. DO NOT use a mercury or dial-type
thermometer.
2. Connect pressure gage to discharge line near compressor.
3. After unit conditions have stabilized, read head pressure on
discharge line gage.
NOTE: Operate unit a minimum of 15 minutes before checking
charge.
4. From standard field-supplied Pressure-Temperature chart for
R-410A, find equivalent saturated condensing temperature.
5. Read liquid line temperature on thermometer; then subtract
from saturated condensing temperature. The difference
equals subcooling temperature.
6. Compare the subcooling temperature with the normal tem-
perature listed in Tables 16-28. If the measured liquid line
temperature does not agree with the required liquid line tem-
perature, ADD refrigerant to raise the temperature or
REMOVE refrigerant (using standard practices) to lower the
temperature (allow a tolerance of ± 3°F).
Refrigerant Charging
NOTE: Do not vent or depressurize unit refrigerant to atmosphere.
Remove and recover refrigerant following accepted practices.
Air Coil Fan Motor Removal
Disconnect motor power wires from motor terminals before motor
is removed from unit.
1. Shut off unit main power supply and apply lock-out/tag-out.
2. Loosen bolts on mounting bracket so that fan belt can be
removed.
3. Loosen and remove the 2 motor mounting bracket bolts on
left side of bracket.
4. Slide motor/bracket assembly to extreme right and lift out
through space between fan scroll and side frame. Rest motor
on a high platform such as a step ladder. Do not allow motor
to hang by its power wires.
TROUBLESHOOTING
When troubleshooting problems with a WSHP, consider the fol-
lowing.
UNIT PROTECTION MODULE (UPM)
Each unit is factory provided with a UPM board that controls the
compressor operation and monitors the safeties. The UPM board
should be one of the first areas to start with troubleshooting an
equipment issue. See Fig. 28.
Fig. 28 — Unit Protection Module (UPM)
WARNING
To prevent personal injury, wear safety glasses and gloves
when handling refrigerant. Do not overcharge system — this
can cause compressor flooding.
CAUTION
Before attempting to remove fan motors or motor mounts,
place a piece of plywood over evaporator coils to prevent coil
damage.
S
UCTION
PUMP
S
UPPORT
TANK
FINE ME
S
H
S
CREEN
RETURN
GA
S
VENT
PUMP
PRIMING
CONN.
GLOBE
VALVE
S
S
UPPLY
1
”
PIPE
CONDEN
S
ER
REMOVE WATER
REGULATING VALVE
1
2
3
4
5
6
7
9
10
11
12
13
17
14
15
16
8
1
Board Power Indicator
2
UPM Status LED Indicator
3
Water Coil Freeze Protection Temperature Selection
[R30]
4
Air Coil Freeze Protection Temperature Selection
5
UPM Settings
6
Water Coil Freeze Connection
7
Air Coil Freeze Connection
8
LED Status-Diagnostic Connection
9
24VAC Power Input
10
Compressor Contact Output
11
High Pressure Switch Connection
12
Call for Compressor Y1
13
Low Pressure Switch Connection
14
24VAC Power Common
15
Condensate Overflow Sensor
16
Dry Contact
17
UPM Ground Standoff