User Guide

SERVICE GUIDE
Some Helpful
Guidelines
Using the LED
Indicators
Detecting
24vac Shorts
Isolating
24vac Shorts
Dampers Not
Responding
Properly
HVAC System
Not Responding
Properly
All voltage measurements on the
NCM300 panel should be made with
the ground lead of your meter on
terminal “C” of the 24VAC input
terminals.
All voltage measurements at the HVAC
System Terminal Block (W1/B, O, Y,
W2/E & G) should be made with the
meter’s ground lead on the terminal
“C” at the HVAC system block.
The STATUS LED should blink at
1second on / 1 second off, to indicate
the microprocessor is operating
properly.
The SUPPLY AIR LIMIT LED will
illuminate if the panel senses a
discharge temperature in excess of the
high or low limit set points. The LED will
blink rapidly if the sensor is open,
shorted or disconnected. The panel
will function normally but with no
supply air temperature control until the
open or short is repaired.
The Zone Damper LED’s will
illuminate to indicate which dampers
should be open.
The W1/B LED indicates that the panel
is in the 1st stage heating mode or, the
“B” type reversing valve output is
active.
The W2/E LED indicates 2nd stage
heat or Emergency heat has been
energized.
The COMPRESSOR LED indicates
the compressor is energized.
The FAN LED indicates the fan is
energized.
All LED’s will be off and the panel
will appear to be dead! you will
measure 24VAC at the transformer
terminals R & C, but not at any damper
M1&M2 terminals, or any zone
the rmost at R & C ter mina ls.
CAUTION: The thermal breaker will be
hot to the touch.
Remove the power to the panel and
allow the thermal poly fuse to cool
down.
Remove the wire at each zone
thermostat R terminal and test if the
short still persists by restoring power to
the zone panel and testing as
described above. If the short dis-
appears, check the zone thermostat
wiring and the thermostat itself. This
applies if the thermostat requires the
24 volt (C)common, or the R wire could
be shorted to the building ground.
If the Zone LED indicators are
illuminated but the dampers appear to
be malfunctioning, check the damper
field wiring.
If the ZONE LED’s are not responding
properly, check the calls on each zone
thermostat. If the calls indicate a
damper should be energized and is
not, press the RESET button to cancel
the timers. If the problem persists, see
Table 2 for service help.
If the HVAC LED indicators are
responding properly, but the system
appears to be malfunctioning, check
that the HVAC system is wired correctly
and that the DIP switches have been
properly set.
If the HVAC LEDs are not responding
properly, check the calls on each zone
thermostat. If the calls indicate that the
HVAC system should be activated and
is not, press the RESET switch to
cancel the timers. Also check that the
DIP switches have been properly set. If
the problem persists, see Table 3 for
trouble shooting help.
6
Table 1. Detecting 24VAC Shorts
If the short still persists disconnect all
the wires at each damper terminal (M1,
M2, M4 & M6). Restore power and test
as described above. If the short clears,
check the damper wiring and the
dampers for shorts with a continuity
tester. If the short still persists, call the
technical support hot-line.
Check 24VAC
Power
Measure 24VAC at all damper M1 and
M2 terminals and all T-stat R and C
terminals. See Table 1 if any of these
voltages are incorrect.
EWC Controls Inc. 385 Highway 33 Englishtown, NJ 07726 800-446-3110 FAX [phone] E-Mail- [e-mail]