Refrigerator Not Cooling On Dc - Norcold 322 Repair Manual

Refrigerator Not Cooling on DC

If the refrigerator is not cooling with the Selector
switch in the DC mode - yet cools in the other
modes - the DC heater is probably not energized.
Check the following:
1. Check for 12 volts to the heater at DC heater Ter-
minals 3 (+) and 4 (-). See Figure 3 for location.
If there is no reading, the possibilities are a) DC
supply not connected, b) 20 Amp fuse blown,
c) wiring connections, or d) defective Selector
switch. Proceed to Step 2.
If voltage is measured (10.5-15.4 volts), then the
heater or the wiring to the heater is defective or
the heater is not positioned properly in the heater
well. Proceed to the Continuity Test in Step 4.
2. If no heater voltage is measured, check condi-
tion of the 20 Amp fuse (should be 0 Ohms us-
ing an Ohmmeter set at lowest scale); replace if
necessary and repeat Step 1 to insure there is
no secondary problem. If fuse blows a second
time, go to Step 4 since it indicates either a
WARNING
shorted heater or a grounding fault.
NEVER OVER FUSE A CIRCUIT. REPLACE
BLOWN FUSE WITH EXACT REPLACEMENT IN-
DICATED BY NORCOLD. OVER FUSING OF A
CIRCUIT CAN RESULT IN A FIRE.
3. If the fuse is good, reinstall fuse and check the
Supply voltage at Terminal 5 (-) and 6 (+). See
Figure 3 for location. If no reading or if the voltage
is outside the limits of 10.5 Volts min. and 15.4
Volts max., correct the power source. If there is
still no voltage at the heater terminals (Terminals 3
& 4), the problem is an open circuit either in the
Control assembly or the interconnecting wiring.
Using the wiring diagram as reference, check
the wiring for loose connections or incorrect con-
nections. If a check of wiring proves OK, the
open circuit is either in the Thermostat or Selec-
tor Switch. Isolate the problem as follows:
a. With the AC and DC power disconnected, un-
fasten the Control Assembly and lay back to
view the control wiring - per removal proce-
dure on page 12-18. Without removing any
wires, place a jumper across terminals W1 &
W2 as illustrated in Figure 5.
Note: Access to the terminals can gained by
probing through the end of the Quick
Connectors as shown in the illustrations.
If the DC heater is now energized when
power is applied, replace the Thermostat. If
not, remove jumper and go to (b.) below.
b. With the AC and DC power disconnected, lay
back the Control panel as described in Step
(a) and place one jumper from DC2 to W2
and another jumper from DC1 to W1 accord-
ing to Figure 15. If DC is now energized when
power is applied, replace the Selector Switch
GAS-AC-DC
Selector Switch
Figure 15 - Selector Switch with Jumper on DC Section
per replacement procedure on page12-20.
4. Ground Fault Test: With the Selector switch still
in the DC position, disconnect the DC Supply at
Terminals 5 and 6. Use an Ohmmeter (set on
highest scale) to measure resistance between
Terminal 6 and chassis ground (metal panel will
work), as illustrated in Figure 16. Read the
Ohmmeter and refer to TABLE 3 on page 12-16.
Continuity Test: With the Selector switch still in
the DC position and the DC Supply discon-
nected at Terminals 5 & 6, use an Ohmmeter to
measure resistance between Terminals 5 & 6,
as in Figure 17. Read the Ohmmeter and refer
to TABLE 3 on page 12-16.
5. If the Ground Fault or the Continuity Test meas-
ures a short (0 Ohms), this causes the 20 Amp
fuse to blow. Repeat the test where 0 Ohms was
measured but this time with the DC heater dis-
connected (Reason: to determine whether the
short is in the heater or the controls).
If the Ohmmeter still shows a short (0 Ohms), the
control assembly has a short and must be re-
placed. See page 12-18 for replacement procedure.
If the Ohmmeter now shows an open circuit, the
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