Diagnostic Error Messages
The controller runs background tests during normal operation. If a problem with the background tests occurs, an error
message is shown (flashing) in the Display. These are called Diagnostic Error Messages (Table 3).
Display
Corrective Action
rPLC
rSET
OPEn
r TC
Oven temperature has
not reached at least
200˚F(93˚C) within 15
minutes of operation.
Usually a result of the
burner not lighting.
1. Turn Blower Switch OFF for 2
minutes, then Turn Blower Switch
ON.
2. If problem does not clear, call
the Middleby Cooking Systems
Group (MCSG) for assistance.
Caused by an
open circuit in the
thermocouple circuit.
1. Check that the thermocouple is
connected to terminals 7 & 8 of the
temperature controller.
2. If connections are good, then check
the continuity of the thermocouple at
room temperature. The resistance
reading should be in the 9 - 20 Ohm
range. Remove & replace an open
thermocouple.
3. If the thermocouple checks good,
call MCSG for assistance.
Reverse polarity of the
thermocouple leads.
1. Check the polarity of the
thermocouple leads; terminal 7 (-)
RED wire & terminal 8 (+) WHITE
wire.
2. If polarity connections are
correct replace thermocouple.
Flashes on the display
alternately with
temperature indicating
that the controller’s
internal diagnostics test
has failed.
1. Turn Blower Switch OFF for 2
minutes, then Turn Blower Switch
ON.
2. Replace the controller if the
problem does not clear after repeating
action 1 above three times.
Table 3 - Diagnostic Error Messages
Oven temperature has
not reached at least
200˚F(93˚C) within 15
minutes of operation;
usually a result of the
burner not lighting.
Middleby Marshall Inc. • 1400 Toastmaster Drive • Elgin, IL 60120 • (847) 741-3300 • FAX (847) 741-4406
Middleby Corporation 24 Hour Service Hotline 1-800-238-8444
©1997 Middleby Marshall Inc.
Part # 36622
Page 11 of 11
P 9/97, Rev. B
