14
3. If Y1 is energized, and compressor no. 1 is already
energized and the room thermostat calls for Y2,
compressor no. 1 continues to operate. If Y2 remains
energized for more than 20 minutes, compressor no. 2
is energized.
NOTE: Compressor no. 2 cannot be energized unless there is a
signal for Y2 from the space thermostat.
4. If compressor no. 2 is energized, and the Y2 signal
from the thermostat is satisfied, compressor no. 1 and
2 are deenergized. If the thermostat reenergizes Y2
will start compressor no. 1 and (after the 2-minute
interstage delay) compressor no. 2.
5. If compressor no. 1 is energized and the thermostat is
satisfied, compressor no. 1, the OFM, and IFM are
deenergized and the EconoMi$er modulates closed.
When the OAT is below the MECH CLG LOCKOUT set
point, the compressors remain off.
HEATING — When the room thermostat calls for heat, the
heating controls are energized as described in the rooftop unit
Installation, Start-Up and Service Instructions.The IFM is ener-
gized and the EconoMi$er damper modulates to the minimum
position. When the thermostat is satisfied, the damper modu-
lates closed.
VENTILATION (CONTINUOUS FAN) — When the room
thermostat is set for continuous fan, the EconoMi$er damper
remains at minimum position as long as the IFM is energized.
When the IFM cycles off, the damper modulates closed.
VENTILATION CONTROL — If a CO
2
sensor is connected
to the EconoMi$er controller and the IFM is energized, the
EconoMi$er minimum position increases if the CO
2
level is
greater than the CO
2
set point. The set point is adjustable
between 800 and 1,400 ppm through the CO
2
SP potentiometer
located on the EconoMi$er control. The greater the difference
between the actual CO
2
level and the set point, the greater
amount the damper modulates open.
SUPPLY AIR LOW LIMIT — The Supply Air Low Limit
(SALL) control strategy is used to protect the mechanical
equipment. The SALL will override the minimum position set
point and the damper command from the ventilation control
strategy if SAT drops below 45 F. The outdoor-air damper is
completely closed when the SAT reaches 35 F. If mechanical
cooling is energized, it will stay energized.
TROUBLESHOOTING
NOTE: Refer to Tables 5-7 for troubleshooting information.
LED Indication —
The EconoMi$er controller features an
onboard diagnostic LED (light-emitting diode) that flashes to
indicate its status. See Table 6 for flash codes. The controller
also has terminal connections (REM LED) for remotely mount-
ing an LED, if desired. The flash code priorities are as follows:
1. On/Off or continuous flash
2. Critical fault
3. Non critical fault
If any sensors are opened, shorted, or removed, the
EconoMi$er determines whether the failure is critical or non-
critical and flashes the appropriate code. See Table 7 for proce-
dures. If a non-critical sensor fault occurs (i.e., outdoor air
humidity), the EconoMi$er automatically reconfigures its con-
trol strategy to a more appropriate mode. If a critical sensor
fault occurs (i.e., supply air sensor), the EconoMi$er reverts to
a safe mode of operation until the sensor problem is resolved.
See Table 6.
Manual Configuration Pushbutton —
The
EconoMi$er controller also features an onboard pushbutton
(CONFIG) to help troubleshoot the system. Pressing this but-
ton for more than three seconds, but less than ten seconds and
then releasing will start the automatic test procedure. The
damper will modulate fully open, wait, and modulate closed.
This process takes three minutes to complete. Use this feature
to determine if the actuator can be commanded.
If the CONFIG button is pressed and held for ten seconds or
more then released, the EconoMi$er controller reconfigures its
mode of operation based on the sensors that are connected and
functioning normally, and cancels the automatic test procedure.
If the EconoMi$er controller recognized a non-critical
sensor fault, and flashed a code (i.e., FLASH 6, outdoor air
humidity sensor fault) the FLASH CODE will be cleared, and
normal operation begins. Ensure faulty sensor is removed
before clearing faults.
If the EconoMi$er controller recognizes a critical sensor
fault, and flashes a code (i.e., FLASH 4, supply air sensor fault)
the FLASH code will not be cleared, and the EconoMi$er will
remain in the safe operation mode. The sensor fault must be
corrected to enable EconoMi$er to revert to normal operation.
Sensor Characteristics —
The discharge air, outdoor air,
and return air temperature sensors are Negative Temperature
Coefficient (NTC) type. Their respective temperature versus
resistance values are shown in Table 5.
The OA and RA humidity sensors have an output signal of
0 to 5 VDC based upon a relative humidity value of 0 to 100%.
See Fig. 46.
The CO
2
input of 2 to 10 VDC is based upon a 0 to
2000 ppm and shown in Fig. 47.
Table 5 — Temperature vs Resistance
DEGREES F
DEGREE C
RESISTANCE
0
–18
19,208
10
–12
14,062
20
–7
10,408
30
–1
7,784
40
4
5,880
50
10
4,484
60
16
3,450
70
21
2,678
80
27
2,095
90
32
1,652
100
38
1,313
5
4
3
2
1
0
0%
20%
40%
60%
80%
100%
RELATIVE HUMIDITY (RH)
VDC
VDC
0
500
1000
1500
2000
10
8
6
4
2
0
PARTS PER MILLION (ppm)
Fig. 46 — Output Signal vs Relative Humidity
Fig. 47 — Output Signal vs CO
2
(ppm)
