Dometic NDA1402 - Limited Three-Year Warranty Dometic Refrigerators

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5.14 Fuses
The NDA/NDE 1402 use (4) DC fuses to protect the cir-
cuit board from internal/external DC shorts. The 5 amp AC
(glass) fuse is designed to protect the integrity of the AC
detection and heater circuit from shorts. All fuses should
be checked for continuity with the fuse removed from the
board. If a fuse blows don’t replace it, until the problem
has been found. If a fuse blows there is a short or compo-
nent that has created the problem.
5.13 Lower Board
ALL TESTS ARE TO BE DONE WITH THE REFRIGER-
ATOR IN THE COOLING MODE.
Unplug both thermistors from the control board dur-
ing lower board testing to assure the unit is calling
for cooling.
DC Volts
Measure the DC voltage between terminal (J2) positive
(+) and (J1) ground (–) on the main control board. The
voltage should be the same as at the positive (+) and
negative (–) terminals on the DC input terminal block. 8.5
volts minimum to 18 volts maximum would be the operat-
ing range. If the voltage is outside the 8.5 volts minimum
to 18 volts maximum, check the power supply, terminal
block and correct the power source before going on with
the test.
AC Mode
Test the upper control board and the 5-wire harness before
testing for proper AC operation. Check that the incoming
AC voltage is present between terminals J10 (black) and
J7 (white) on the lower circuit board. If no voltage is pres-
ent, check wiring and the coach power supply. If voltage is
present, and with the unit on AC operation, check for volt-
age at the heating element connection terminals (J8) and
(J9) on the circuit board. If no voltage is present, discon-
nect 120 volt AC and 12 volt DC and check the 5 amp AC
(F5) and 3 amp DC (F2) fuses, wiring harness and upper
control. If AC volts are present between (J7) and (J10),
and no voltage on (J8) and (J9) the AC voltage detection
circuit is damaged and the control board will need to be
changed.
Gas Mode
Note: All current Dometic control boards are 3 try sys-
tems in the gas mode. There is a 2 minute purge cycle
between each trial for ignition. Flame failure could take 6
to 7 minutes.
Verify that the following components are good: upper cir-
cuit board, thermistor, wire harness and 3-amp fuse (F2).
First, check for voltage during trial-for-ignition at Plug P6,
Terminal 2 (yellow wire +) to the ignition control module.
If no voltage is present change the main circuit board. If
voltage is present and there is no spark, test the ignition
control module. See section 5.8 for diagnosis.
NOTE: A loose ground will create erratic or no gas op-
eration on all systems.
This is an energized circuit. Shock can occur
if not tested properly. Testing is to be done
by a qualied service technician.
The power module is the main control unit that acts as the
heart of the electronic control system. It performs power
ON/OFF control, energy selection, thermostatic operation
control and defrosting control. All other electrical parts
are connected to the power module. See section 11 for
trouble shooting any error codes.
J1- is the ground (–) connection.
•
J2 is the 12 volt DC (+) battery voltage input into •
the power module.
J3 and J4 are connected in parallel and are sup-•
plying 12 volt DC (+) to the door frame heater and
the anti-freezing system for the ice maker water
supply line.
J5- is the DC voltage output to the defrosting ele-•
ment in the freezer.
J6- is the 120 volt AC neutral connection for the •
ice maker.
J7- is the 120 volt AC main supply neutral con-•
nection.
J8- is the 120 volt AC neutral connection for the •
AC heaters in the cooling unit.
J9- is the 120 volt AC main line connection for the •
AC heaters in the cooling unit.
J10- is the 120 volt AC main supply line connec-•
tion.
J11-is the 120 volt AC line voltage to the inter-•
face module if using a single power cord.
Tab connectors from left to right (at the bottom edge of the
main control board)
Fuses (From left to right, on the lower board)
Always refer to the wiring diagram for the model/product
number to determine the “Type of component” designa-
tion.
If the unit has a separate power cord for the ice-maker,
(J6) and (J11) will not be used.
Fuse Type of component
(F2) 3 amp A, B, C, E, G, H, P, R
(F6) 7.5 amp S, T
(F3) 3 amp W (optional icemaker kit)
(F4) 7.5 amp X
(F5) 5 amp Z