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6. Tighten setscrews and replace panel(s).
7. Turn on unit power.
UNIT SIZE
020-035, 050
040, 060
Fig. 47 — Condenser-Fan Adjustment
(All Units Except Size 060 MCHX)
Four-Inch Filter Replacement —
Change Mode variable is used to service the unit when 4-in.
filters are used. When the filters need to be changed, set
Service Test
F.4.CH = YES. The unit will be placed in
Service Test mode and the economizer will move to the 40%
open position to facilitate removal of the 4-in. filters. After the
filters have been changed, set Service Test
return the unit to normal operation.
The economizer damper motor is a
Power Failure —
spring return design. In event of power failure, dampers will
return to fully closed position until power is restored.
Refrigerant Charge —
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 refriger-
ant 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 111.
NOTE: Indoor-air cfm must be within normal operating range
of unit.
A
DIMENSION "A" (in.)
1.30 ± 0.12
0.87 ± 0.12
The 4-Inch Filter
F.4.CH = NO to
Amount of refrigerant charge is
Table 111 — Round Tube, Plate Fin Unit Charge
UNIT
REFRIGERANT
48/50
A2,A3,A4,A5
48/50A2,A3,A4,A5 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
require more accurate measurement techniques. Charge should
be added in small increments. Using cooling charging charts
provided (Fig. 48-54), 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
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 con-
densing temperature (available on the ComfortLink 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 Sys-
tem — 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
minutes by switching RHV to ON through the Service
Test function (Service Test
3. At the end of the 5-minute period, switch back into Cool-
ing mode through the Service Test function (Service
Test
COOL
4. Using the cooling charging charts provided (Fig. 48-54),
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
paragraph "To Use the Cooling Charging Chart" for addi-
tional instructions.
5. If a charge adjustment was necessary in Step 4, then re-
peat the steps in this paragraph (starting with Step 2) until
no charge adjustment is necessary. When no more charge
adjustment is necessary after switching from a Dehumidi-
fication Mode to a Cooling Mode (Steps 2 and 3), then
the charge adjustment procedure is complete.
Thermostatic Expansion Valve (TXV)
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.
134
SIZE
TYPE
020, 027, 040,
050, 060
R-410A
030, 035
025
1
/
4
COOL
RHV).
RHV) by switching RHV to OFF.
1
/
lb increments until complete. See
4
Each circuit has
LIQUID
SUBCOOLING
15 F ± 2 F
20 F ± 2 F
12 F ± 2 F
lb increments
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