9
present, the inverter needs to be replaced, or internal wiring
is incorrect. If line voltage is absent, check for 24 vac across
the main contactor coil, and verify line voltage between the
lower terminals of the contactor. If 24 volt coil voltage is absent,
check continuity through the high pressure switch, and verify
that the
COMMUNICATIONS PORT
plug is in place at
J6
at
the bottom edge right of the interface board.
No Control Board Display
If the 2-character display on the interface board shows nothing,
verify that 24 vac control voltage is present between
R
and
C
(red and black wires of the field wiring harness plugged into the
right side of the control board. If voltage is absent, check field
wiring back to the indoor unit and transformer and thermostat.
If voltage is present but the display is blank, the control board
needs to be replaced. Check wiring for indications of a direct
short before trying a new board.
Troubleshooting Individual Fault Codes (when
active)
Follow the recommended troubleshooting procedures in Table
8 for “active” faults. In some cases more than one fault code
or different active codes may be generated by one issue, e.g.
interruption of line power. Always cycle line power (30 seconds
off, then on for at least 1 minute) to confirm that an active fault
returns, is re-declared, before considering replacing hardware.
Most inverter-related faults are at least temporarily cleared by
cycling power in this manner. Do not replace hardware based
on history alone, on faults that are not “active”.
Table 8. Individual Fault Codes
CODES
DESCRIPTION
1
9
These codes indicate abnormal high current or high
inverter temperature. If they persist and return as active
fault codes, they may indicate a faulty inverter drive or a
wrong interface board/inverter combination.
Compressor Drive Failure
– This generally indicates
a compressor problem which may be temporary or
permanent. If the compressor has just been replaced,
recheck the U, V, and W compressor leads for a
connection mistake. Before the inverter declares this
fault during an attempted startup, it will try to start the
compressor 4 times, with approximately 20 seconds
pause between attempts. During start attempts, listen
for compressor noise; if none, the compressor may need
to be replaced. Check compressor phase-to-phase
resistances; they should all be less than 1.5 ohms
and within 0.2
Ω
of each other. If compressor noise is
loud, squealing, or otherwise unusual, the compressor
may need to be replaced. If the compressor restarts
normally, this fault code may be simply an indication that
the compressor speed has been temporarily disrupted
by either starting or shutting down abruptly against a
high pressure ratio. In either case, the system may
be normal but only temporarily affected by abnormal
running conditions.
4
1
11
1
1
These fault codes refer to internal inverter operation and
are likely to indicate inverter failure. If they persist and
return as active fault codes, replace the inverter assembly.
6
High DC Bus Voltage
– This is an indication that line
voltage exceeded 10% over nominal value. The cause
is likely to be power grid abnormalities or a poorly
controlled generator.
7
low DC Bus Voltage
– In most cases this is an
indication that 208/230 volt line power was interrupted
or disconnected. It may also indicate low line voltage
or, rarely, an internal inverter failure.
8
low AC line Voltage
– This indicates that line voltage
has dropped below approximately 170 volts. It may also
indicate loss of line power, in which case Code
7
may
appear in addition to or instead of this code.
14
Loss of Communication Between Inverter and
Interface Board
– Check the inverter LEDs (as
described in Inverter Circuit Board LEDs section) for
an indication that the inverter has line power. Follow the
troubleshooting steps described in that section first. If
the inverter LEDs are lit but the code is active, verify that
the 4-pin plug at
J5
(InVERtER PORt
) is connected at
the bottom edge center of the interface board. If these
checks do not resolve the fault and the fault remains
active, replace the interface board.
1
16
17
These are warning codes that simply indicate that a
high current or temperature condition was reached,
and that the inverter was able to keep the parameter in
an acceptable range by automatically reducing speed.
These conditions do not result in the unit shutting down
(unless the current or temperature increased further
and reached a shutdown limit, in which case another
code would be displayed).
NOTE:
If a high current or
temperature shutdown occurs, these warning codes are
not necessarily displayed and stored.
