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Table 21 — PARABLADE Economizer Troubleshooting
PROBLEM CAUSE REMEDY
Damper does not
open.
Evaporator fan not on. Check wiring between G on connection board and indoor (evaporator) fan
contactor.
No power to economizer
motor.
1. Disconnect power at TR and TR1. Disconnect jumper across P and P1.
2. Connect jumper across TR and 1.
3. Connect jumper across T1 and T.
4. If connected, remove enthalpy sensor from terminals S
O
and +.
5. Apply power (24 vac) to terminals TR and TR1. The LED should be off and
the damper should be in the closed position.
6. Disconnect the factory-installed 620 ohm resistor from terminals S
R
and +.
The LED should light up and the motor should drive towards open. If this
does not happen, replace the economizer control module.
Economizer motor failure. If the indoor (evaporator) fan and economizer motor are energized, verify that
there is a minimum of 24 vac at terminals TR and TR1. If the motor is not oper-
ating, replace the motor.
Economizer op-
eration limited to
minimum position.
Economizer control module
failure.
1. To simulate high or low enthalpy, reconnect the factory-installed 620 ohm
resistor across terminals S
R
and +.
2. Connect 1.2 Kohm checkout resistor across terminals S
O
and +. Turn the
enthalpy set point to ‘‘A.’’ The LED should turn on, indicating low enthalpy.
The motor should drive towards open. If LED does not light, replace module.
If motor does not drive open, check motor operation.
3. Turn the enthalpy set point to ‘‘D.’’ The LED should turn off, indicating high
enthalpy. The motor should drive towards closed. If these actions do not oc-
cur, replace module.
4. Disconnect 1.2 Kohm checkout resistor before resuming operation.
Damper does not
close.
No power to economizer. 1. Disconnect power at TR and TR1. Disconnect jumper across P and P1.
2. Connect jumper across TR and 1.
3. Connect jumper across T1 and T.
4. If connected, remove enthalpy sensor from terminals S
O
and +. Factory-
installed 620 ohm resistor should be connected to terminals S
R
and +.
5. Apply power (24 vac) to terminals TR and TR1. The LED should be off and
the damper should be in the closed position.
6. Disconnect the factory-installed 620 ohm resistor from terminals S
R
and +.
The LED should light up and the motor should drive towards open. If this
does not happen, replace the economizer control module.
Spring return failure. If power to unit is off and damper does not close, check for a bound linkage. If
linkage is not bound, then internal spring may be broken. Replace
actuator.
Economizer motor failure. If the economizer control module is functioning properly, verify that there is a
minimum of 24 vac at terminals TR and TR1. If the motor is not operating, re-
place the motor.
Damper does not
open or close
according to
enthalpy readings.
Sensor incorrectly wired or
bad.
To verify sensor operation, reconnect the + lead of the outdoor enthalpy sensor
to the + terminal of the economizer control module. Connect a DC milliammeter
between terminals S
O
of the economizer control module and terminals S of the
enthalpy sensor. The milliammeter should indicate between 3 and 25 mA if the
sensor is operating properly. If the milliammeter indicates 0, the sensor may be
wired backwards. If any other readings are shown, replace the sensor.
LED — Light-Emitting Diode
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