Service manual
Bulletin #46 continued
The circuit board on the AES also has the ability to monitor the 12 volt supply voltage.
If the incoming voltage to the refrigerator drops below 9.5
(+-
1) volts, the AES will
switch to gas operation and the refrigerator will be unaffected by the thermostat.
Until
the low voltage situation is corrected, the system will remain on
gas
continually and will
not switch to 120 or 12 volt and overcooling or freezing will probably occur.
As a
warning device. the green indicator light will shut off during the voltage drop.
When
the incoming voltage returns to 12 volts, the green indicator lamp will switch back on
and the refrigerator will again return to the most suitable energy source.
It
must be
remembered that the AES requires 12 volts at all times to operate on 120 volts, I2
volt
or gas.
When a problem with the refrigerator system is being diagnosed and it is suspected that
the circuit board is at fault, most likely the failure will be visible on the board itself.
If the AES fails to operate and it is noted that there is a shorted wire between diodes
or a shorted or burned section of the connecting foil on the circuit board, it is probable
that this circuit board is defective.
Be sure the troubleshooting steps outlined below are
followed BEFORE changing the board.
The AES Analyzer (Part
#800-0006-00/0)
also may
be used to test the printed circuit boards.
HEATERS
MODEL
OHM’S READING
3800
&
1303 AES
42
Ohm’s
3600
& 763 54
Ohm’s
3500
&
663 AES
82
Ohm’s
The 120 and 12 volt heaters that are included in the AES refrigerator contain a quick
connect contact plug
-
for ease of replacement.
These plugs are polarized and will fit
only one way.
When checking the electric element, you should notice a 42 ohm’s reading
with the 3800 and 1303 AES; 54 ohms on the 3600 and 763; and 82 ohms on the 3500 and
663 AES.
With these models on
12V
operation,
the heaters will draw 22.9, 20.8 and 15.8
amps respectively.
SOLENOID VALVE
FIG. 3
12
VOLT SOLENOID VALVE
The AES uses a thermo-electric solenoid valve for opening
and closing the gas supply line instead of the usual
manually operated safety valve. When the refrigerator is
ready to light on gas, the circuit board will send 12 volts
to the solenoid valve to open it. After the flame is lit
the millivolts supplied from the thermocouple will keep
the solenoid valve open.
The 12 volt signal current from
the circuit board will drop off in IO-20 seconds after the
flame is lit.
To check the valve for operation, disconnect
the braided cable plug from the solenoid valve. Connect a
jumper wire from the 12 volt positive terminal on the
refrigerator to the lower lug on the solenoid valve. When
this is done, an audible click should be heard. This
indicates that the valve is operational. The solenoid valve should be replaced if it does
not click open.
If the valve opens, the D.C. voltage from the igniter must be checked.
T
O open the solenoid valve,
there must be a positive pulse voltage between the yellow
wire on the igniter (marked L) and ground.
This pulse voltage is supplied by the
igniter. It should be noted that the resistance cannot be checked across the terminals When
the solenoid valve without damaging the circuit board if the braided cable is connected.
A-9-2