33
OVEN SYSTEMS
Impingement System
The impingement system rapidly heats, filters, and
recirculates air into the cook cavity.
This section contains information about the
following components:
- Blower motor
- Blower motor speed controller (BMSC)
- Heater - top
- Heater - bottom
- High-limit thermostat
- Jetplate - bottom
- RTD - top and bottom
- Solid state relay (K4/K5 - Heaters)
For information on accessing and removing parts,
see the Appendix.
Blower Motor
The blower motor is a brushless AC-switch
reluctance type and spins clockwise. Its top speed
is 7,100 RPM at 1 HP, and it is controlled by a
proprietary controller (see below).
Blower Motor Speed Controller (BMSC)
The motor controller is proprietary and will only
operate the motor described above. It is controlled
via 0-10 VDC speed command from the control
board and can be tested in Test Mode (see page 20).
Heater - Top
The top heater is an open-coil heater rated at 3,300
watts at 208 VAC, with a resistance of 13 Ω. The
top heater is controlled by K5 of the K4/K5 solid
state relay. For testing instructions, see page 19.
Heater - Bottom
The bottom heater is a sheathed-style heater rated
at 3,000 watts at 208 VAC, with a resistance of
14.4 Ω. The bottom heater is controlled by the K4
of the K4/K5 solid state relay. For testing instruc-
tions, see page 19.
High Limit Thermostat
The high limit thermostat is a 250 VAC, 3-pole,
manual-reset thermostat with a trip point of 572
º
F
(300
º
C). The thermostat interrupts power to the
bottom or top heater in the event of an abnormal
condition. Reset the high-limit thermostat by
pressing the reset button on the back oven wall,
near the power cord.
Jetplate - Bottom
The bottom jetplate channels air from the blower
motor into the cavity. It is removable for cleaning.
NOTE: The top jetplate is not removable.
RTD - Top and Bottom
One RTD measures the temperature of the top
heater, and another RTD measures the tem-
perature of the bottom heater. If the display reads
“999°F/C”, at least one RTD is open, resulting in
an F7 fault. See page 51 for troubleshooting.
Testing Procedure:
1. Disconnect the RTD from the control
harness (see page 64 for schematic).
2. Place the RTD in ice water for two minutes.
3. Take a resistance reading of the RTD.
4. If RTD resistance is not 100 Ω (+/- 2 Ω), the
RTD is defective and must be replaced.
Solid State Relay - K4/K5 Heaters
The solid state relay is a 240 VAC, dual 40-amp
relay. K4 switches power to the bottom heater, and
K5 switches power to the top heater.
Troubleshooting
The following faults may occur in relation to the
convection system:
- F1: Blower (see page 47)
- F2: Low Temp (see page 48)
- F6: EC Temp (see page 51)
- F7: Thermo (see page 51)
- F8: Heat Low (see page 52)
- F9: CC Temp (see page 52)
The following cooking performance issues may
occur in relation to the convection system:
- Food not cooking properly (see page 60)
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