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15
VENTILATION AIR (Minimum Position Set Up) — If ven-
tilation air is not required, skip this section. If ventilation air is
required, perform the following:
1. The indoor fan must be on to set the ventilation air.
Either put the thermostat in the continuous fan mode or
jumper the R and G terminals at the rooftop unit con-
nection board.
2. Locate the minimum position (MIN POS) potentiometer.
Turn the potentiometer full CCW to fully close the out-
door air dampers. Turn the potentiometer gradually
clockwise (CW) to the desired position. See Fig. 16.
3. Replace the filter access panel. See Fig. 18. Ensure the fil-
ter access panel is securely engaged.
4. Calculate the minimum airflow across the EconoMi$er.
a.
Calculate % of outside air using the following
formula.
% Outdoor air through EconoMi$er
b. Multiply total CFM by percentage outdoor air, this
gives outdoor air volume in CFM.
Step 9 — Install All Accessories —
After all the
factory-installed options have been adjusted, install all field-
installed accessories. Refer to the accessory installation instruc-
tions included with each accessory.
MOTORMASTER® III CONTROL INSTALLATION
Install Field-Fabricated Wind Baffles — Wind baffles must
be field-fabricated for all units to ensure proper cooling cycle
operation at low ambient temperatures. See Fig. 25 for baffle
details. Use 20-gage, galvanized sheet metal, or similar
corrosion-resistant metal for baffles. Use field-supplied screws
to attach baffles to unit. Screws should be 6.3 mm (
1
/
4
-in.)
diameter and 15.9 mm (
5
/
8
-in.) long. Drill required screw holes
for mounting baffles.
Install Motormaster III Controls — Only one Motormaster
III control is required per unit.
Sensor — Install the sensor for thermistor input control in the
location shown in Fig. 26 and 27. Connect sensor leads to the
purple and grey control signal leads on the Motormaster III
control.
Signal Selection Switch — Remove the cover of the Motor-
master III control. Set the switch to accept the thermistor
sensor input signal. Set the frequency to match the unit power
supply (50 Hz).
% Outdoor air =
Mixture Temp – Return Air Temp
Outdoor Temp – Return Air Temp
Personal Injury Hazard. Avoid possible injury by keep-
ing fingers away from damper blades.
To avoid damage to the refrigerant coils and electrical com-
ponents, use recommended screw sizes only. Use care
when drilling holes.
20 mA LED
1k ohm Potentiometer
2 to 10 VDC at
0 to 2000 ppm
CO2 Sensors:
Rem ote
M inim um Position
Rem ote
LED
Outdoor Air Enthalpy
CROUTENT001A00
Return Air Enthalpy
CRRETENT001A00
Line
Voltage
CO
CO
COM
DAT
COM
REM
POT
COM
LED
COM
2
2
OAT
COM
OAH
+15V
RAT
COM
RAH
+15V
C
O
M PW
O
U
T T
T
Violet
C
O
M PW
O
U
T T
T
Violet
Field-supplied W iring
W iring Included
470 ohm
5 watt
Resistor
24 VAC m ust be present
on BI for the system to be
unoccupied.
Unoccupied
Contact
Tan
Violet
W hite
Red
Tan
Violet
W hite
Red
24 V
A
C
20 V
A
NOT
USED
1
2
-
(+)
3
2
3ZCSENCO
Unoccupied Control
Fig. 24 — Typical EconoMi$er Sensor Wiring