Bryant 677D--A, Руководство по установке

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CONTROL FAULT
If the HP/AC control board has failed, the control will flash the
appropriate fault code (See Table 4). The control board should be
replaced.
BROWN OUT PROTECTION
If the line voltage is less than 187v for at least 4 seconds, the
appropriate compressor contactor and fan relay are de--energized.
Compressor and fan operation are not allowed until voltage is a
minimum of 190v. The control will flash the appropriate fault
code (See Table 4).
230V LINE (POWER DISCONNECT) DETECTION
If there is no 230v at the compressor contactor when the unit is
powered and cooling demand exists, the appropriate error code is
displayed. Verify that the disconnect is closed and 230v wiring is
connected to the unit.
COMPRESSOR VOLTAGE SENSING
The control board input terminals VS and L2 (See Fig. 19) are
used to detect compressor voltage status, and alert the user of
potential problems. The control continuously monitors the high
voltage on the run capacitor of the compressor motor. Voltage
should be present any time the compressor contactor is energized,
and voltage should not be present when the contactor is
de--energized.
CONTACTOR SHORTED DETECTION
If there is compressor voltage sensed when there is no demand for
compressor operation, the contactor may be stuck closed or there is
a wiring error. The control will flash the appropriate fault code.
COMPRESSOR THERMAL CUTOUT
If the control senses the compressor voltage after start--up, and is
then absent for 10 consecutive seconds while cooling demand
exists, the thermal protector is open. The control de--energizes the
compressor contactor for 15 minutes, but continues to operate the
outdoor fan. The control Status LED will flash the appropriate
code shown in Table 4. After 15 minutes, with a call for low or
high stage cooling, the compressor contactor is energized. If the
thermal protector has not re--set, the outdoor fan is turned off. If
the call for cooling continues, the control will energize the
compressor contactor every 15 minutes. If the thermal protector
closes (at the next 15 minute interval), check the unit will resume
operation.
If the thermal cutout trips for three consecutive cycles, then unit
operation is locked out for 4 hours and the appropriate fault code is
displayed.
NO 230V AT COMPRESSOR
If the compressor voltage is not sensed when the compressor
should be starting, the contactor may be stuck open or there is a
wiring error. The control will flash the appropriate fault code.
Check the contactor and control box wiring.
TROUBLESHOOTING UNIT FOR PROPER SWITCHING
BETWEEN LOW & HIGH STAGES
Check the suction pressures at the service valves. Suction pressure
should be reduced by 3--10% when switching from low to high
capacity.
NOTE
: The liquid pressures are very similar between low and
high stage operation, so liquid pressure should not be used for
troubleshooting.
Compressor current should increase 20--45% when switching from
low to high stage. The compressor solenoid, when energized in
high stage, should measure 24vac.
COMPRESSOR INTERNAL RELIEF
The compressor is protected by an internal pressure relief (IPR)
which relieves discharge gas into compressor shell when
differential between suction and discharge pressures exceeds 550 --
625 psig. The compressor is also protected by an internal overload
attached to motor windings.
TEMPERATURE THERMISTORS
Thermistors are electronic devices which sense temperature. As the
temperature increases, the resistance decreases. Thermistors are
used to sense outdoor ambient (OAT) and coil temperature (OCT).
Refer to Fig. 29 for resistance values versus temperature. See Fig.
30 for OCT location.
0
10
20
30
40
50
60
70
80
90
0 20 40 60 80 100 120
TEMPERATURE (DEG. F)
RESISTANCE (KOHMS)
THERMISTOR CURVE
A91431
Fig. 29 -- Resistance Values Versus Temperature
If the outdoor ambient or coil thermistor should fail, the HP/AC
control will flash the appropriate fault code (See Table 4).
IMPORTANT : Coil thermistor is factory mounted. Check to
insure thermistor is mounted properly. Outdoor air thermistor
(OAT) is field mounted and connected by two black leads (located
in the control section)on the outdoor control board. Verify that the
OAT has been properly installed.
THERMISTOR SENSOR COMPARISON
The control continuously monitors and compares the outdoor air
temperature sensor and outdoor coil temperature sensor to ensure
proper operating conditions. The comparison is:
S
In cooling mode, if the outdoor air sensor indicates
≥
10
_
F
(5.5
_
C) warmer than the coil sensor (or) the outdoor air sensor
indicates
≥
20
_
F (11
_
C) cooler than the coil sensor, the sensors
are out of range.
S
In heating
i
f the outdoor air sensor indicates
≥
35
_
F (19.3
_
C)
warmer than the coil sensor (or) the outdoor air sensor indicates
≥
10
_
F (5.5
_
C) cooler than the coil sensor, the sensors are out of
range.
If the sensors are out of range, the control will flash the appropriate
fault code as shown in Table 4.
The thermistor comparison is not performed during low ambient
cooling operation.
FAILED THERMISTOR DEFAULT OPERATION
Factory defaults have been provided in the event of failure of
outdoor air thermistor and/or coil thermistor.
If the OAT sensor should fail, low ambient cooling will not be
allowed and the one--minute outdoor fan off delay will not occur.
Defrost will be initiated based on coil temperature and time.
If the OCT sensor should fail, low ambient cooling will not be
allowed. Defrost will occur at each time interval during heating
operation, but will terminate after 5 minutes.
If there is a thermistor out of range error, defrost will occur at each
time interval during heating operation, but will terminate after 5
minutes.
Refer to the Troubleshooting Chart (Tables 9--11) for additional
troubleshooting information.
677D
--
--
A