Dc Ground Fault/Continuity Check - Norcold 322 Repair Manual

TABLE 3

DC Ground Fault/Continuity Check

Test Points
Terminal 6 & Chassis
See Figure 16
Terminal 6 & Chassis
See Figure 16
Terminal 5 & 6
See Figure 17
Terminals 5 & 6
See Figure 17
Terminals 5 & 6
See Figure 17
Terminals 5 & 6
See Figure 17
* If the heater is hot when the measurement is taken, the correct resistance range is 1.3 - 1.47 Ohms.
short is in the heater and must be replaced.
6. If the Continuity Test indicated in TABLE 3
measures an open, remove the heater leads at
Terminals 3 & 4 and install a jumper across ter-
minals 3 & 4 (See Figure 17 for location). Re-
peat the Continuity Check.
If after installing the jumper, the Ohmmeter
now shows a short, the heater has the open
circuit and must be replaced. Remove jumper
from terminals 3 & 4.
If the Ohmmeter still shows an open, there is
an open circuit in the control panel (make sure
the Selector switch is still in the DC position).
The control assembly should be pulled out to
make sure all the wiring is correct. See page
12-18 for removal procedure and wiring dia-
grams to aide in tracing the wiring connec-
tions. Remove jumper from terminal 3 & 4. If a
check of wiring proves OK, either the Thermo-
stat or the Selector is has an open circuit. Iso-
late the open circuit 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 procedure
Ohmmeter Reading
0 Ohms
(dead short)
Open Circuit
1.21 - 1.37 Ohms*
above 1.37 Ohms or
below 1.21 ohms
0 Ohms
(dead short)
Open Circuit
(no reading)
16
Indication
Indicates a grounding fault
Normal condition
Heater is good
Heater is out of tolerance
Indicates a short in the
AC circuit
Indicates an open in the
AC circuit
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 be 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 above
and place one jumper from DC2 to W2 and
another jumper from DC1 to W1 according to
Figure 15. If DC is now energized when
power is applied, replace the Selector Switch
per replacement procedure on page 12-20.
7. If the continuity test in Step 4 indicates normal
heater ohms (1.21-1.37), then the problem is not
in the electrical circuit. Make sure the supply
voltage is within 10.4 to 15.4 volts range with the
heater operating, and check heater position to
insure it is securely installed in its well.
Action
Go to Step 5
Possibility of ground
fault is eliminated
Go to Step 7
Replace heater per
replacement procedure
on page 12-17
Go to Step 5
Go to Step 6