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Power Failure
The economizer damper motor is a spring return design. In
event of power failure, dampers will return to fully closed posi-
tion until power is restored.
Refrigerant Charge
Amount of refrigerant charge is listed on unit nameplate. Refer
to Carrier GTAC II; Module 5; Charging, Recovery, Recycling,
and Reclamation section for charging methods and procedures.
Unit panels must be in place when unit is operating during
charging procedure.
NOTE: Do not use recycled refrigerant as it may contain
contaminants.
NO CHARGE
Use standard evacuating techniques. After evacuating system,
weigh in the specified amount of refrigerant from the unit
nameplate.
LOW CHARGE COOLING
All Units with Round Tube-Plate Fin Condenser Coils
Connect the gage set and a temperature-measuring device to the
liquid line. Ensure that all condenser fans are operating. It may
be necessary to block part of the coil on cold days to ensure that
condensing pressures are high enough to turn on the fans. Adjust
the refrigerant charge in each circuit to obtain state point liquid
subcooling for specific models as listed in Table 110.
NOTE: Indoor-air cfm must be within normal operating range of
unit.
Table 110 — Round Tube, Plate Fin Unit Charge
48/50A Units with MCHX Condenser
Due to the compact, all aluminum design, microchannel heat
exchangers will reduce refrigerant charge and overall operating
weight. As a result, charging procedures for MCHX units re-
quire more accurate measurement techniques. Charge should
be added in small increments. Using cooling charging charts
provided (Fig. 49-55), add or remove refrigerant until
conditions of the chart are met. As conditions get close to the
point on the chart, add or remove charge in
1
/
4
lb increments
until complete. Ensure that all fans are on and all compressors
are running when using charging charts.
To Use the Cooling Charging Chart
Use the outdoor air temperature, saturated suction temperature
and saturated condensing temperature (available on the
Com-
fort
Link display), and find the intersection point on the cooling
charging chart. If intersection point is above the line, carefully
recover some of the refrigerant. If intersection point is below
the line, carefully add refrigerant.
NOTE: Indoor-air cfm must be within normal operating range of
unit.
Units with Humidi-MiZer Adaptive Dehumidification System
All circuits must be running in normal cooling mode. Indoor
airflow must be within specified air quantity limits for cooling.
All outdoor fans must be on and running at normal speed.
Use the following procedure to adjust charge on Circuit B of
Humidi-MiZer equipped units:
1. Start all compressors and outdoor fans. Allow unit to run for
5 minutes.
2. Switch system to run in a Dehumidification mode for 5 min-
utes by switching
RHV
to ON through the Service Test func-
tion (
Service Test
COOL
RHV
).
3. At the end of the 5-minute period, switch back into Cooling
mode through the Service Test function (
Service Test
COOL
RHV
) by switching RHV to OFF.
4. Using the cooling charging charts provided (Fig. 49-55), add
or remove refrigerant until conditions of the chart are met.
As conditions get close to the point on the chart, add or re-
move charge in
1
/
4
lb increments until complete. See para-
graph "To Use the Cooling Charging Chart" for additional
instructions.
5. If a charge adjustment was necessary in Step 4, then repeat
the steps in this paragraph (starting with Step 2) until no
charge adjustment is necessary. When no more charge ad-
justment is necessary after switching from a Dehumidifica-
tion Mode to a Cooling Mode (Steps 2 and 3), then the
charge adjustment procedure is complete.
Thermostatic Expansion Valve (TXV)
Each circuit has a TXV. The TXV is adjustable and is factory
set to maintain 8 to 12°F superheat leaving the evaporator coil.
The TXV controls flow of liquid refrigerant to the evaporator
coils. Adjusting the TXV is not recommended.
UNIT
48/50
REFRIGERANT
TYPE
SIZE
LIQUID
SUBCOOLING
A
R-410A
020, 027, 040,
050, 060
15°F ± 2°F
030, 035
20°F ± 2°F
025
12°F ± 2°F
Summary of Contents for WEATHERMAKER 48A2020
Page 112: ...112 Fig 20 Typical Main Control Box Wiring Schematic 48 50A Units ...
Page 113: ...113 Fig 21 Typical Auxiliary Control Box Wiring Schematic ...
Page 114: ...114 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown ...
Page 115: ...115 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown TO NEXT PAGE ...
Page 116: ...116 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont ...
Page 117: ...117 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown ...
Page 118: ...118 Fig 25 Typical Controls Option Wiring Schematic SW1 SW2 OR DEHUMIDIFY SWITCH ...
Page 119: ...119 Fig 26 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown ...
Page 120: ...120 Fig 27 Typical Power Schematic of Greenspeed Low Ambient Option 48 50A 060 Unit Shown ...
Page 121: ...121 Fig 28 Typical Small Chassis Component Location Size 020 035 Units ...
Page 122: ...122 Fig 29 Typical Large Chassis Component Locations Size 040 060 Units ...
Page 185: ...185 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716 ...