Bryant 558D Installation, Start-Up And Service Instructions Manual page 34

PROBLEM
Damper does not Evaporator fan not on.
open.
No power to economizer
motor.
Economizer motor failure.
Economizer op- Economizer control module
eration limited to failure.
minimum position.
Damper does not No power to economizer.
close.
Spring return failure.
Economizer motor failure.
Damper does not Sensor incorrectly wired or
open or close bad.
according to
enthalpy readings.
LED — Light-Emitting Diode
Table 21 — PARABLADE Economizer Troubleshooting
CAUSE
Check wiring between G on connection board and indoor (evaporator) fan
contactor.
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
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
The LED should light up and the motor should drive towards open. If this
does not happen, replace the economizer control module.
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.
1. To simulate high or low enthalpy, reconnect the factory-installed 620 ohm
resistor across terminals S
2. Connect 1.2 Kohm checkout resistor across terminals S
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.
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
installed 620 ohm resistor should be connected to terminals S
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
The LED should light up and the motor should drive towards open. If this
does not happen, replace the economizer control module.
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.
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.
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
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.
—34—
REMEDY
and +.
R
of the economizer control module and terminals S of the
O
and +.
O
and +.
R
and +. Turn the
O
and +. Factory-
O
and +.
R
and +.
R