Crankcase heater, Evaporator fan, Condenser fans and motors – Carrier 48AJ User Manual
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• DIP switch 6 configures the Time Guard® override and,
when used with the field test function, sets the minimum
damper position
• DIP switch 7 configures the unit for gas heat or electric
heat
• DIP switch 8 configures the unit for heat pump or air
conditioner operation.
Crankcase Heater —
Units are equipped with crank-
case heaters. Crankcase heaters are energized as long as there is
power supplied to unit. Crankcase heaters deenergize while
compressors are running.
Evaporator Fan —
Fan belt and fixed pulleys are
factory-installed. See Tables 19-33 for fan performance and
motor limitations data. Remove tape from fan pulley, and be
sure that fans rotate in the proper direction. See Table 34 for air
quantity limits. Static pressure drop for power exhaust is negli-
gible. To alter fan performance, see Evaporator Fan Perfor-
mance Adjustment section on page 91.
Condenser Fans and Motors —
Condenser fans and
motors are factory set. Refer to Condenser-Fan Adjustment
section on page 92 as required. Be sure that fans rotate in the
proper direction. Fan no. 2 (48AJ,AK,AW,AY020-030 and
48EJ,EK,EW,EY024-034), fans no. 3 and 4 (48AJ,AK,AW,
AY035-050 and 48EJ,EK,EW,EY038-054), and fans no. 4, 5,
and 6 (48AJ,AK,AW,AY060 and 48EJ,EK,EW,EY058-068)
are cycled on the outdoor-air temperature.
The VFD will always provide the proper phase sequence to
the indoor-fan motor to operate in the proper rotation regard-
less of the phase sequence to the unit. If on start-up, the outdoor
fans operate backwards but the indoor fan operates in the cor-
rect direction, reverse any two leads to the unit main terminal
block and all fans will operate in the correct direction.
Table 16A — Power Exhaust Default Set Points (48AJ,AK,AW,AY020-050 and 48EJ,EK,EW,EY024-048)
Table 16B — Power Exhaust Default Set Points (48AJ,AK,AW,AY060 and 48EJ,EK,EW,EY054-068)
Table 17 — DIP Switch Configuration
LEGEND
NOTES:
1. The OPEN side of the DIP switch is marked ‘‘OPEN.’’ When the
rocker switch is on the ‘‘OPEN’’ side of the switch, the switch is
OPEN.
2. The configuration of DIP switches 2 and 5 are dependent on
DIP switch 1. If DIP switch 1 is set to OPEN (VAV operation),
then DIP switches 2 and 5 will configure VAV functions.
3. When the unit is field-tested (DIP switch 4 to OPEN), the func-
tion of DIP switch 6 changes and it is used to set the minimum
damper position.
4. Recycle power to unit after modifying DIP switches. This will
allow the unit to access the new configurations and update its
tables.
IMPORTANT: To prevent damage to compressors, crank-
case heater should be energized 24-hours prior to start-up.
STAGE
OFFSET
DIFFERENTIAL
OFF VOLTAGE
ON VOLTAGE
OFF STATIC PRESSURE
(in.wg)
1
50%
3%
6.0
6.3
0.00
2
55%
3%
6.5
6.8
0.06
3
60%
3%
7.0
7.3
0.12
4
64%
3%
7.4
7.7
0.18
STAGE
OFFSET
DIFFERENTIAL
OFF VOLTAGE
ON VOLTAGE
OFF STATIC PRESSURE
(in.wg)
1
50%
3%
6.0
6.3
0.00
2
55%
3%
6.5
6.8
0.06
3
60%
3%
7.0
7.3
0.12
4
65%
3%
7.5
7.8
0.19
5
70%
3%
8.0
8.3
0.25
6
75%
3%
8.5
8.8
0.31
SETTING
1
2
3
4
5
6
7
8
OPEN
VAV
VAV — Space Sensor
Installed
Expansion
Board
Field Test
ON
VAV —
Occupied
Heat
Enabled
Time Guard® Override
ON
Gas Heat
Heat Pump
Operation
CV — CCN or Sensors
Used
CV —
Modulated
Power
Exhaust
IN CONJUNCTION
WITH FIELD TEST
— Set Minimum
Damper Position
CLOSED
CV
VAV — No Space Sensor
Base Control
Board Only
Field Test
OFF
VAV —
Occupied
Heat
Disabled
Time Guard Override
OFF
Electric Heat
Air Conditioner
Operation
CV — Thermostat
CV —
Constant
Volume
Power
Exhaust
CCN — Carrier Comfort Network
CV
— Constant Volume
VAV — Variable Air Volume