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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)
*
For single enthalpy control, the module compares outdoor
enthalpy to the ABCD set point.
†
Power at N terminal determines Occupied/Unoccupied setting:
24 vac (Occupied), no power (Unoccupied).
**
Modulation is based on the supply-air sensor signal.
††
Modulation is based on the DCV signal.
***
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).
††† 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$er IV can be used for free cooling. The sensor has 8
selectable temperature changeover setpoints, ranging from
48°F to 78°F. The temperature changeover is set using the 3
dip switches on the sensor See Fig. 56.
Fig. 56 — C7660 Temperature Sensor
Table 11 — EconoMi$er IV Input/Output Logic
Compressor
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
OUTPUTS
Stage 2
Occupied
On
Off
Minimum position
Off
Off
Modulating** (between
min. position and full-open)
Off
Off
Minimum position
On
Modulating†† (between min.
Off
position and DCV maximum)
Off
Off
Off
Modulating***
Off
Supply Air Temperature (SAT) Sensor
The supply air temperature sensor is a field-installed 3 K thermis-
tor located on the fan deck. See Fig. 57. 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 12 on page 33 for sensor tem-
perature/resistance values.
SUPPLY AIR
TEMPERATURE
SENSOR
Fig. 57 — 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 tem-
perature. See Fig. 51 on page 29.
32
N Terminal†
Unoccupied
Closed
Modulating** (between
closed and full-open)
Closed
Modulating†† (between
closed and DCV maximum)
Modulating†††
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Troubleshooting
