Carrier 42NQV009E Service Manual page 55

10-4-2. Caution at servicing
(1) After servicing, push the [START/STOP] button to return to the normal mode.
(2) After servicing by the check code, turn off breaker of the power supply, and turn on breaker of the power
supply again so that memory in the microcomputer returns the initial status. However, the check codes are
not deleted even if the power supply is turned off because they are stored in the fixed memory.
Block distinction
Check Check
Block
code code
Indoor
P.C. board
Not
displayed
Connect-
ing cable
and serial
signal
Table 10-4-1
Operation of diagnosis function
Cause of operation
Short-circuit or disconnec-
tion of the room temperature
sensor (TA sensor).
Being out of place,
disconnection, short-circuit,
or migration of heat
exchanger sensor
(TC sensor)
Lock of indoor fan or trouble
on the indoor fan circuit
Trouble on other indoor
P.C. boards
Return serial signal is not
sent to indoor side from
operation started.
(1) Defective wiring of
connecting cable
(2) Operation of compressor
thermo.
Gas shortage
Gas leak
Operation command signal
is not sent to outdoor side.
Air conditioner
Remark
status
Operation Displayed when
continues. error is detected.
Operation Displayed when
continues. error is detected.
All off Displayed when
error is detected.
Operation Displayed when
continues. error is detected.
Operation Flashes when
continues. trouble is
detected on
Return serial
signal, and
normal status
when signal is
reset.
Operation Flashes when
continues. trouble is
detected on
Operation
command signal,
and normal status
when signal is
reset.
– 54 –
FILE NO. SVM-07018
Judgement and action
1. Check the room temp. sensor.
2 When the room temp. sensor is
normal, check P.C. board.
1. Check heat exchanger sensor.
2. When heat exchanger sensor is
normal, check P.C. board.
1. Check P.C. board.
2. When P.C. board is normal, check
the motor.
Replace P.C. board.
1. When the outdoor unit never
operate:
(1) Check connecting cable, and
correct if defective wiring.
(2) Check 25A fuse of inverter
P.C. board
(3) Check 3.15A of inverter
P.C. board.
2. To display [Other] block during
operation, check compressor
thermo. operation and supply gas
(check gas leak also).
3. Unit operates normally during
check.
If Return serial signal does not
stop between 2 and 3 of the
indoor terminal block, replace
inverter P.C. board. If signal stops
between 2 and 3 of the indoor
terminal block, replace indoor P.C.
board.
If Return serial signal does not stop
between 2 and 3 of the indoor
terminal block, replace inverter P.C.
board. If signal stops between 2 and
3 of the indoor terminal block,
replace indoor P.C. board.