Watlow EZ-ZONE
®
PMI Controller • 228 • Chapter 11 Appendix
Indication Description Possible Cause(s) Corrective Action
Autotuning
tUn1
tUn2
Controller is
autotuning the con-
trol loop
• User started the
autotune function
• Digital input is set to
start autotune
• Wait until autotune com-
pletes or disable autotune
feature
• Set digital input to func-
tion other than autotune,
if desired
No heat/cool
action
Output does not ac-
tivate load
• Output function is incor-
rectly set
• Control mode is incor-
rectly set
• Output is incorrectly
wired
• Load, power or fuse is
open
• Control set point is incor-
rect
• Incorrect controller mod-
el for application
• Set output function cor-
rectly
• Set control mode appro-
priately (Open vs Closed
Loop)
• Correct output wiring
• Correct fault in system
• Set control set point in
appropriate control mode
and check source of set
point: remote, idle, pro-
file, closed loop, open
loop
• Obtain correct controller
model for application
No Display No display indica-
tion or LED illumi-
nation
• Power to controller is off
• Fuse open
• Breaker tripped
• Safety interlock switch
open
• Separate system limit
control activated
• Wiring error
• Incorrect voltage to con-
troller
• Turn on power
• Replace fuse
• Reset breaker
• Close interlock switch
• Reset limit
• Correct wiring issue
• Apply correct voltage,
check part number
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