Bunn TWIN APS, Operating & Service Manual

Page: 14 / 32

Page 14
TROUBLESHOOTING (cont.)
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
4. Temperature Probe
5. Limit Thermostat
6. Tank Heater
1. Lime build up on temperature
probe, tank or tank heater
Remove the probe from the grom-
met and submerge in a water bath
of approximately 70
°
F(21
°
C). Con-
nect 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 reading should
be 9.3k
±
2k OHMS. If the probe is
within these parameters, recon-
nect the J3 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 25)
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 26)
Inspect probe and tank assembly
for excessive lime deposits. Delime
as required.
PROBABLE CAUSE REMEDY
HEATING CIRCUIT
PROBLEM
36672 030104