Carrier 50FC 04 Series Service And Maintenance Instructions page 35

INPUTS
Demand Enthalpy
Controlled
Ventilation
Outdoor
(DCV)
High
(Free Cooling
LED Off)
Below set
(DCV LED
Off)
Low
(Free Cooling
LED On)
High
(Free Cooling
LED Off)
Above set
(DCV LED
On)
Low
(Free Cooling
LED On)
NOTE(S):
a. For single enthalpy control, the module compares outdoor enthalpy to the ABCD set point.
b. Power at N terminal determines Occupied/Unoccupied setting: 24 vac (Occupied), no power (Unoccupied).
c. Modulation is based on the supply-air sensor signal.
d. Modulation is based on the DCV signal.
e. Modulation is based on the greater of DCV and supply-air sensor signals, between minimum position and either maximum position (DCV) or fully open (supply-air signal).
f. Modulation is based on the greater of DCV and supply-air sensor signals, between closed and either maximum position (DCV) or fully open (supply-air signal).
Outdoor Air Temperature (OAT) Sensor
The outdoor air temperature sensor (HH57AC074) is a 10 to
20 mA device used to measure the outdoor-air temperature. The
outdoor-air temperature is used to determine when the
EconoMi$er IV can be used for free cooling. The sensor has
8 selectable temperature changeover setpoints, ranging from 48°F
to 78°F. The temperature changeover is set using the 3 DIP
switches on the sensor See Fig. 62.
Fig. 62 — C7660 Temperature Sensor
Supply Air Temperature (SAT) Sensor
The supply air temperature sensor is a field-installed 3K thermis-
tor located on the fan deck. See Fig. 63. This sensor is factory in-
stalled. The operating range of temperature measurement is 0°F to
158°F (–18°C to 70°C). See Table 7 for sensor temperature/resis-
tance values.
Table 6 — EconoMi$er IV Input/Output Logic
a
Y1 Y2
Return Stage 1
On On On
Low On Off On
Off Off Off
On On On
High On Off Off
Off Off Off
On On On
Low On Off On
Off Off Off
On On On
High On Off Off
Off Off Off
Compressor
Stage 2 Occupied
On
Off Minimum position
Off
Off
Modulating
position and full-open)
Off
Off Minimum position
On
Modulating
Off
position and DCV maximum)
Off
Off
Off Modulating
Off
Supply Air
Temperature
Sensor
Fig. 63 — Supply Air Sensor Location
The temperature sensor looks like an eyelet terminal with wires
running to it. The sensor is located in the "crimp end" and is sealed
from moisture.
Outdoor Air Lockout Sensor
The EconoMi$er IV is equipped with an ambient temperature
lockout switch located in the outdoor airstream which is used to
lock out the compressors below a 42°F (6°C) ambient tempera-
ture. See Fig. 57 on page 32.
35
OUTPUTS
N Terminal b
Unoccupied
(between minimum Modulating
c
closed and full-open)
d (between minimum Modulating
closed and DCV maximum)
e
Closed
(between
c
Closed
d (between
Modulating f