Economizer Checkout - Lennox Prodigy 2.0 Application Manual

7.10. Economizer Checkout

The following checkout procedures are completed with unit energized. Confirm proper operation of the heartbeat LED. Step
1 will determine whether the economizer is allowing full damper travel. Use step 2 when the damper does not respond to step
1.
Steps 3, 4, 5, and 6 checkout the operating modes; checkout only the mode that applies to the unit being worked on.
Power exhaust fans will be functional. To prevent operation of power exhaust fans, disconnect power to unit and then
PED jack/plug P/J18.:
Step 1. ECONOMIZER OUTPUT VOLTAGE
The M3 Unit Controller monitors P262 (DPOS) and operates as reference in Section 18.3.2. Damper Diagnostics.
A Go to SERVICE > TEST > DAMPER>POSITION > DAMPER POSITION ACTUAL: 0.0% The motor will slowly
modulate to the closed position.
B Change DAMPER POSITION ACTUAL to 100.0%.The motor will slowly modulate to the fully opened position.
C If the motor does not respond, go to step 2. If the motor does respond properly, go to the appropriate mode of
operation checkout.
Step 2. OUTPUT VOLTAGE CHECK
A Go to SERVICE > TEST > DAMPER > POSITION > DAMPER POSITION ACTUAL: 0.0%
B Adjust the DAMPER POSITION ACTUAL: to 0.0% position.
C Measure the voltage on P262 between pin 3 (VOT damper control) and pin 2 (GND) using pin 1 as common.
Voltage should read approximately 2 VDC.
D Adjust the DAMPER POSITION ACTUAL: to 100.0% position.
NOTE - Allow approximately 90 seconds for actuator to react.
E Measure the voltage between P262 between pin 3 (VOT damper control) and pin 2 (GND) using pin 1 as
common. Voltage should read approximately 10 volts DC. If not, check wiring and trouble shoot system.
Step 3. SINGLE ENTHALPY OPERATION (ODE)
In the single enthalpy mode, dampers open for free cooling when the outdoor enthalpy is less than the enthalpy set point
(Parameter 162 - ECON FREECL ENTH SP); 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).
A Go to SETUP > INSTALL > press SAVE until you get to the Configuration ID 1, position 2 needs to be set to S for
Economizer ­ Single Enthalpy and press SAVE.
B To simulate low outdoor enthalpy. Disconnect A7 outdoor enthalpy sensor jack/plugs J/P104. Connect a 750 ohm
resistor across plug J104-1 and J104-2. J104 is located in the filter access area.
C Check all connections and wiring between J104 and the control.
Step 4. DUAL ENTHALPY MODE OF OPERATION
In dual enthalpy mode mode, dampers open for free cooling when the outdoor air enthalpy is lower than the return air
enthalpy by difference value of (Parameter 163 - ECN FRCL ENTH OFFST); dampers will modulate discharge air
temperature (RT6) to (Parameter 159 - FREE COOL SUPPLY SP) which has a default setting of 55.0°F (13°C).
A Go to SETUP > INSTALL > press SAVE until you get to the Configuration ID 1 position 2 needs to be set to D for
Economizer ­ Dual Enthalpy and press SAVE if performing an economizer field-install.
B Use two resistors to simulate outdoor air enthalpy suitable.
•
Disconnect A62 return air enthalpy sensor jack/plug J/P105. Place a 1500 ohm resistor between J105-1 and
J105-3. J/P105 is located in the filter access area.
•
Disconnect A7 outdoor enthalpy sensor jack/plugs J/P104. Connect a 750 ohm resistor across J104-1 and
J104-2.
CAUTION
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