Carbon Dioxide Sensor
ppm as shown in the following table. The sensor is powered with 24VAC
TABLE 3 
Carbon Dioxide Range
Carbon Dioxide 
PPM
DCV
Carbon Dioxide 
PPM
DC Voltage Carbon Dioxide 
PPM
DC Voltage Carbon Dioxide 
PPM
DCV
0
0 
3 1200  1800 
200
1 800
4 1400 7 2000 10
400
2 1000
5  8
VAV Supply Static Sensor
                
0-5”w.c as shown in the following table. The sensor is powered with 24VAC.
TABLE 4 
Static Pressure
Pressure “w.c. DCV Pressure “w.c. DC Voltage Pressure “w.c. DC Voltage Pressure “w.c. DCV
0
0 1.5
3 3  4.5 
0.5
1 2
4 3.5 7 5 10
1
2 2.5
5 4 8
Relative Humidity Sensor - Optional
        
sensor with a 0-10VDC output over a relative humidity 
range of 0-100% relative humidity. The sensor is powered 
with 24VAC.
Enthalpy Sensor - Optional
        
the economizer have an output of 4-20mA. The sensor is 
powered with 18VAC provided by M3 unit control.
        
Pressure Transducer (PT5) present in the economizer. 
       
-
sponding to 0” water column and 2” water column respec-
tively. For all practical purposes the output should be less 
than 1.2” water column if not an error code is stored and 
service alarm output is turned on.
16-Second-Stage Power Exhaust Relay K231 
 The second power exhaust fan is controlled by K231. 
A133 will enable K231 only when the blower reaches 70% 
of full speed (adjustable ECTO). This prevents a nega-
tive building pressure when the blower is operating in low 
speed. Refer to the Unit Controller manual and ECTO la-
bels on the unit.
auto voltage to 230VAC transformers are mounted in the 
control box. The transformers have an output rating of 
0.5A. T5 transformer supplies 230 VAC power to outdoor 
outdoor fans B22, B23 and B24.
provides overcurrent protection to compressor and other 
        
sheet metal enclosure in the unit left front corner mullion.
19-Blower Motor Overload Relay S42
The relay (S42) is connected in line with the blower motor 
senses an overload condition, a set of normally closed 
A55 Unit Controller. A55 de-energizes all outputs. Units 
will be equipped with a relay manufactured by Teleme-