Lennox Prodigy 2.0 Application Manual page 39

Step 5. ALL TEMPERATURE MODES OF OPERATION
In the Economizer – Temperature mode, the damper opens for free cooling when the outdoor air temperature is:
•
Less than return air temperature by at least a difference of (Parameter 161 - ECON FRCL TMP OFFST) if Temperature
Offset mode is selected
•
Less than (Parameter 160 - ECON FREECL TEMP SP)
In all modes, dampers will try to modulate discharge air temperature (RT6) to (Parameter 159 - FREE COOL SUPPLY SP)
which has a default setting of 55.0°F (13°C).
Refer to the "Displaying Sensor Inputs" section to read return air (RT16) and outdoor air (RT17) temperatures. If outdoor air
is not cooler than return air, simulate a colder outdoor air temperature with a resistor. Select a resistor value that
corresponds to a temperature (see table 31):
A Locate RT17 sensor in unit. Disconnect 1/4" quick connect terminals on wires leading from sensor.
B Jumper RT17 wires leading back to control with the appropriate resistor.
C Check all connections and wiring between RT17 and the M3 Unit Controller, and between RT16 and the M3 Unit
Controller.
Temp. °F (°C) Size Resistor
30 (-1) 34,566
40 ( 4) 26,106
Step 6. GLOBAL MODULATING (GLO) MODE OF OPERATION
In the GLO (modulating) mode, dampers modulate open for free cooling when the global input is energized; dampers will try
to modulate discharge air temperature (RT6) to (Parameter 159 - FREE COOL SUPPLY SP) which has a default setting of
55.0°F (13°C).
NOTE - The global input turns on the blower.
A Set global mode using the Configuration ID 1, position 2, and set to character G.
B Connect a jumper between A55_P297-1 (24VAC) and A55_P297-9 (global). The blower will be energized and the
damper will slowly open if discharge air temperature (RT6) is greater than (Parameter 159 - FREE COOL SUPPLY
SP) which has a default setting of 55.0°F (13°C).
C Disconnect 24VAC to A55_P297-9. The blower will turn off and the damper will close.
D If the damper does not actuate check all connections and wiring between P262A and B.
Step 7. ENTHALPY SENSOR OPERATION (A7 and A62)
A Connect a direct current ammeter as shown in figure 9 to measure current output of A7 or A62.
DISCONNECT J/P104
Damper Travel: % of Maximum Open
PLACE JUMPER WIRE HERE
-
DC AMMETER
Measure A7 Current in Series
NOTE - If Enthalpy Sensors are configured, current sensor reading by M3 controller can be verified on User interface:
B The reading will be between 4 and 20 ma. depending on outdoor temperature and humidity. Refer to figure 8 to
approximate reading.
Go to DATA > IN/OUTPUTS > SENSORS > LOCAL (scroll down to IE: x.x mA and OE: x.x mA)
C If the meter reads zero, check sensor wiring harness for continuity and/or check polarity of sensor wiring.
Table 31. TMP Mode Resistor Values
Temp. °F (°C) Size Resistor
50 (10) 19,904
60 (16) 15,313
READ
CURRENT
HERE
+
Figure 9. Measure A7 and A62 Current in Series
Temp. °F (°C) Size Resistor
70 (21) 11,884
80 (27) 9,298
DISCONNECT J/P105
PLACE JUMPER WIRE HERE
-
DC AMMETER
Measure A62 Current in Series
Page 39
Temp. °F (°C) Size Resistor
90 (32)
100 (38)
READ
CURRENT
HERE
+
7,332
5,826