Bunn CDBC Operating & Service Manual page 15

TROUBLESHOOTING (cont.)
HEATING CIRCUIT
PROBLEM
Water does not heat to proper
temperature (cont.)
IMPORTANT: Make sure no tem-
perature tests are taken before the
ready light is "ON". Tank tempera-
ture must be stabilized before read-
ings are taken.
Spitting or excessive steaming
PROBABLE CAUSE
4a. Temperature Probe (CDBC)
4b. Temperature Probe (CEZ)
5. Limit Thermostat (CDBC & CEZ)
6. Tank Heater (CDBC & CEZ)
1. Lime build up on temperature
probe, tank or tank heater
Page 15
REMEDY
A) Remove the probe from the
grommet and submerge in a water
bath of approximately 70°F(21°C).
Connect an ohmmeter to pins 3
and 4 of the J3 connector. At
60°F(16°C) the reading should be
15.3k ± 2k OHMS, at 70°F(21°C)
the reading should be 11.8k ± 2k
OHMS, and at 80°F(27°C) the read-
ing should be 9.3k ± 2k OHMS. If
the probe is within these param-
eters, reconnect the J3 plug to the
control board.
B) Remove the probe from the
grommet and submerge in a water
bath of approximately 70°F(21°C).
Connect an ohmmeter to pins 2
and 3 of the J5 connector. At
60°F(16°C) the reading should be
15.3k ± 2k OHMS, at 70°F(21°C)
the reading should be 11.8k ± 2k
OHMS, and at 80°F(27°C) the read-
ing should be 9.3k ± 2k OHMS. If
the probe is within these param-
eters, reconnect the J5 plug to the
control board.
Disconnect the brewer from the
power source. Check for continu-
ity across the limit thermostat ter-
minals. Continuity should be
present. If not replace the limit
thermostat.(See page 28)
Disconnect the brewer from the
power source. Check for continu-
ity between the white terminal of
the terminal block and the black
wire on the relay on the control
board. There should be a low OHM
reading. If no continuity is present,
check for a wiring problem, then
replace the tank heater if no wiring
problem is found.(See page 29)
Inspect probe and tank assembly
for excessive lime deposits. Delime
as required.
29319 091203