48
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 32):
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.
Table 32. TMP Mode Resistor Values
Temp. °F (°C)
Size Resistor
Temp. °F (°C)
Size Resistor
Temp. °F (°C)
Size Resistor
Temp. °F (°C)
Size Resistor
30 (-1)
34,566
50 (10)
19,904
70 (21)
11,884
90 (32)
7,332
40 ( 4)
26,106
60 (16)
15,313
80 (27)
9,298
100 (38)
5,826
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
PLACE JUMPER WIRE HERE
READ
CURRENT
HERE
DC AMMETER
-
+
Damper Travel: % of Maximum Open
DISCONNECT J/P105
PLACE JUMPER WIRE HERE
READ
CURRENT
HERE
DC AMMETER
-
+
Measure A62 Current in Series
Measure A7 Current in Series
Figure 9. Measure A7 and A62 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.
