Moffat turbofan E32SUBC Service Manual page 31

5.3.3 No heat / No temperature
control
Temperature probe faulty
To verify reading refer to 3.4.6
The temperature probe can be tested by measur-
ing it's resistance.Probe must be disconnected for
testing.
Temperature
0°C (32°F)
37°C (99°F)
100°C (212°F)
Element control relay faulty
To test refer to 3.4.6
The element contactor is controlled by relay #2
Check red flag on relay top to see if relay is ener-
gised. If no flag present check voltage (24Vdc) to
control relay coil. If voltage present replace relay.
If relay is operating check continuity through re-
lay contacts. Replace if no continuity through
contacts
Relay #2
Figure 5.3.3a
Electronic control faulty
If no voltage is present at relay coil and controller
is calling for heating on display replace controller.
Heating contactor faulty
With a program selected, check that the heating
contactor coil has voltage across the coil,
terminals A1 and A2. If not check element con-
tactor control relay (#2) and wiring.
If voltage is correct, check that contactor pulls in
and closes the contacts
contactor coil is on. Correct operation will make
an audible noise when closing contacts and on
the front face of
contact mechanism will visibly pull in.
contactor is faulty—replace.
E32SUBC OVEN and PROOFER
Revision 3
Resistance (kΩ)
288
56
6.1
when power to
the contactor the
If not,
Trouble-shooting
If contactor operates
continuity through the poles of the contactor
when closed.
connected poles then contacts are blown and
contactor requires replacing.
Terminal A1
Terminal 1
Terminal 2
For checking elements
overrun is occurring, check that contactor
releases (opens)
switches OFF. If not, contacts of the contactor
have welded shut and elements will be ON and
heating will be continuous. Contactor is faulty—
replace.
Element faulty (blown)
With the controller on and calling for heat check
voltage across element terminals at RH side of
oven. If the voltage is correct then check the
current draw of element. If there is no current
draw then element is faulty—replace.
If there is no voltage then check voltage is
being supplied to each element coil from the
heating contactor.
check contactor operation and wiring.
Correct element current draw:
Inner Coil
Outer Coil
Correct element resistance:
Inner Coil
Outer Coil
27
correctly, check
If no continuity
Terminal A2
Terminal 5
Terminal 6
Figure 5.3.3b
where temperature
when temperature
If no voltage to elements,
9.0A ± 2.5%
11.9A ± 2.5%
26.8 ohms ± 5.0%
20.2 ohms ± 5.0%
© Moffat Ltd, September 2009
5
for
through
control