Troubleshooting Guide - Compu-aire System 2100 Series Installation And Operation Manual

18 TROUBLESHOOTING GUIDE

Complaint
1. System does not run.
Complaint
2. Nothing is visible on
the display or is barely
visible.
3. Temperature or
humidity displayed is
wrong.
Problem
No 24VAC supply
voltage.
System is not turned on. Power LED is on but,
Bad or locked up MCP.
Problem
Display contrast is
adjusted too low.
Sensor circuits are out
of calibration.
Symptom
Power LED is not on.
System LED is off.
Display is blank, shows
erroneous characters or
does not change
messages.
Symptom
Power is on and system
is running okay. But,
nothing is visible or is
barely visible on display.
Displayed value(s) are
wrong by a few
increments.
39
Action
Check circuit breaker in
system 24VAC circuit
and reset if necessary.
Check System cutout
switch. Test for 24VAC
at pins 1 and 2 of MCP.
If no voltage check
machine wiring. Other-
wise, if voltage replaces
MCP.
Press the On button on
the MCP. If the system
does not start and the
display is blank, replace
the MCP.
Press Off button on
MCP then press On
button. If the system
does not start or if the
display still shows
erroneous information,
replace the MCP.
Action
Refer to the section
MCP Circuit
Adjustments, in this
guide. Adjust display
contrast for best
visibility. The display will
not be visible unless
light is directed into it (it
does not have its own
light source).
If the value is wrong by
a few degrees or
percent when
compared to an
accurate measuring
instrument, then try