18
Sizes 04(G--J) to 07(G--J)
Refer to charts (Fig. 36 --39) to determine the proper
leaving condenser liquid temperature at the test c ondition
compressor discharge pressure.
Accurate pressure gauge and temperature sensing meter
are required. Connect the pressure gauge to the service
port on the discharge line. Mount the temperature sensing
devic e on the liquid line leaving the outdoor coil and
insulate it so that out door ambient temperature does not
affect the reading.
Example (Fig. 36):
Unit 04(G--J)
Compressor Discharge Pressure 370psig (2550kPA)
Lea ving Condenser Liquid Temperature 105_F (40.6_C)
NOTE: When using these Perfect Humidity charging
charts, it is important that the system be operating in
Rehea t1 mode: cooling thermostat in demand, humidistat
in demand. The subcooling/reheat dehumidification coil
liquid line solenoid valve MUST be energized to use the
charging charts and the discharge gas reheat solenoid
valve must be de--energized (valve closed). The outdoor
motor speed controller must be jumpered to run the fan at
full speed during charge checking.
Bypass 32LT Motormaster
32LT controller is mounted on a bracket attac hed to unit
base pan beneath the main control box. To bypass the
32LT and run the outdoor fan at full speed:
1. Disconnect power to unit.
2. Remove the 32LT cover to access the splice box.
3. Locate the two line connections with BLK wires.
4. Separate both 32LT BLK leads from control box
BLK wire and the BLK wire from OFM.
5. Splice the control box BLK wire to the OFM wire.
6. Restore power to unit.
When the charge check/adjustment procedure is complete,
restore the 32LT function by disconnecting unit power,
then reversing steps 5 through 2 above, concluding with
repla cing and securing the 32LT cover. Restore power to
the unit.
Charge check and adjustment
Read the discharge pressure gauge; record the pressure.
Read the liquid line temperature. Plot the test discharge
pressure (using the X--axis) and test liquid temperature
(using the Y--axis) on the unit c harging chart. If the
plotted test condition point is to the left/above the
charging curve, add refrigerant. If the plotted test
condition is to the right/below the charging curve,
carefully recover some of the charge.
Allow the unit to operate in Reheat1 mode for
approximately five minutes, then recheck conditions
agai nst the charging chart. Repeat the charge adjustment
procedure until the plotted test condition falls on the
charging curve.
When charging procedure is completed, rem ove the
bypass wiring on the Motormaster control. Readjust the
cooling thermostat setting and the humidistat setting to
appropria te design setpoints.
Sizes 08(K--M) to 14(K--M)
Unit sizes 08(K--M) through 14(K--M) (two circuit
designs) use the same charging chart and general m ethod
as discussed above under Base Cooling Units. See Fig.
30--34. During the charge adjustment step, the unit will be
run in the Cooling mode; thermostat wil l be Cool demand,
humidistat will be open for no demand. The standard
Motormaster head pressure control device will be
jumpered to operate all fans at full speed.
Bypass Motormaster Controllers Unit sizes
08(K--M) to 12(K--M)
32LT controller is mounted on a bracket attac hed to unit
base pan beneath the main control box. To bypass the
32LT and run both outdoor fans at full speed:
1. Disconnect power to unit.
2. Remove the 32LT cover to access the splice box.
3. Locate the two line connections with BLK wires.
4. Separate both 32LT BLK leads from control box
BLK wire and the two BLK wires from OFM1 and
OFM2.
5. Splice the control box BLK wire to the two OFM
wires.
6. Restore power to unit.
When the charge check/adjustment procedure is complete,
restore the 32LT function by disconnecting unit power,
then reversing steps 5 through 2 above, concluding with
repla cing and securing the 32LT cover. Restore power to
the unit.
Unit Size 14(K--M)
Motormaster V (VFD--based) controller provides hea d
pressure control on the size 14(K--M) unit. The c ontroller
is mounted inside the blower compartment, on the wall to
left of blower. Bypassing this controller requires the
fabrication of a resistor--wire assembly consisting of a 10k
ohm (1/2--watt) resistor and two 20--18 ga. wire leads.
To bypass the Motormaster V and run the outdoor fan at
full speed:
1. Disconnect unit power. Lockout/tag--out.
2. Remove MM--V cover to expose the controll er ter-
minal strip.
3. Disconnect the Pressure Transducer input wires at
terminals 2, 5 and 6.
4. Connect the resistor--wire assembly at terminals 5
and 6. See Fig. 22.
5. Replace cover on MM--V.
6. Check for clearances around the blower and be lt.
7. Restore power to unit.
When the charge check/adjustment procedure is complete,
restore the Motormaster V function by disconnecting unit
power, then reversing steps 5 through 2 above. See Fig. 22
580J