1
1
1
1 5
5
5
5
Temp-
4
Unit will not heat over
a temperature that is
below set point
1/ confirm that blower motor is moving and that
amperage and voltage match data plate Ð check blower
motor motion in shadow box and feel for air movement
in chamber
2/ confirm that set point is set high enough Ðturn High
Limitcounter clockwise and see if High Limit light
comes on
3/ check connections to sensor
4/ check calibration Ð using independent reference
thermometer, follow instructions in Watlow users
manual
Temp-
5
Unit will not heat up at
all
1/check amperage Ð amperage should be virtually at
maximum rated (data plate) amperage
2/ do all controller functions work?
3/ is the High Limit set high enough? Ð for diagnostics,
should be fully clockwise with the pilot light never on
4/ has the fuse/circuit breaker blown?
Temp-
6
Indicated chamber
temperature unstable
1/ ±0.1 may be normal
2/ is blower motor working? Ð remove top panel and
verify movement of blower motor in shadow box
3/ is ambient room temperature radically changing Ð
either door opening or room airflow from heaters or air
conditioning ? Ð stabilize ambient conditions
4/ it may happen if exhaust stack is 100% open or if
power exhaust is cycling Ð adjust stack to at least _
closed
5/ sensor miss-located, damaged or wires may be
damaged - check mounts for control and High Limit
sensors, then trace wires between sensors and
controls
6/ calibration sensitivity Ð call Customer Service
7/ high limit set too low Ð be sure that high limit is
more than 5 degrees over desired set point; check if
high limit pilot is on continuously; turn controller knob
completely clockwise to see if problem solved then
follow instructions in section 7.4 for correct setting
8/ electrical noise Ð remove nearby sources of RFI
including motors, arcing relays or radio transmitters
9/ bad connection on temperature sensor or faulty
sensor Ð check connectors for continuity and
mechanical soundness while watching display for
erratic behavior; check sensor and wiring for
mechanical damage
