UZC4
LED’s
The UZC4 is equipped with 18 LED’s which indicate system operation and status. Familiarize
yourself with the LED’s definitions, in order to quickly determine the system status and mode of
operation.
POWER
SAS
OAS
FAN
ZONE 3 OPEN
ZONE 2 OPEN
ZONE 1 OPEN
The POWER LED pulses as a steady heart beat to indicate proper Microprocessor operation.
The OAS LIMIT LED illuminates solid to indicate that the Outdoor Temperature has fallen below the chosen
set point. LED will blink rapidly to indicate a malfunctioning Outdoor Air Sensor.
The SAS LIMIT LED illuminates solid to indicate that the Supply Temperature has exceeded the chosen
set point on either the HIGH TEMP LIMIT or the LOW TEMP LIMIT. LED will blink rapidly
to indicate a malfunctioning Supply Air Sensor.
ZONE 3 LED will illuminate solid to indicate that damper(s) is energized open, and the Zone is active.
ZONE 2 LED will illuminate solid to indicate that damper(s) is energized open, and the Zone is active.
ZONE 1 LED will illuminate solid to indicate that damper(s) is energized open, and the Zone is active.
The FAN LED will illuminate solid to indicate a demand for fan operation, during COOLING, HEATING,
PURGE, or CONTINUOUS FAN operations.
COMPRESSOR 2
W1 HEAT
W2 HEAT
The COMPRESSOR 2 LED illuminates solid to indicate the 2nd stage compressor is energized.
The W1 LED illuminates solid to indicate 1st stage of HEATING is energized in a conventional
HVAC system. Or the W1 LED illuminates solid to indicate the 1st stage of Auxiliary or Backup heat
is energized in a heat pump system. (3rd stage heat) Also illuminates during Emergency mode.
EWC Controls Inc. 385 Highway 33 Englishtown, NJ 07726 800-446-3110 FAX 732-446-5362 E-Mail- info@ewccontrols.com
22
UZC4 LED FUNCTION AND DESCRIPTION
ZONE 4 OPEN
ZONE 4 LED will illuminate solid to indicate that damper(s) is energized open, and the Zone is active.
OA DMPR OPEN
The OA DMPR OPEN LED will illuminate solid to indicate that the Outside Air damper is energized
open in response to the CO2 detector or other device to provide demand based ventilation.
BYPASS DMPR
The BYPASS DMPR LED will illuminate solid to indicate that the Bypass damper(s) is
being forced to the Open position. Occurs during idle, short cycle and changeover periods.
AUX RELAY
The AUX RELAY LED will illuminate solid to indicate that the Auxilary relay is being
energized in response to a demand, to start a function such as Humidify or De-humidify.
COMPRESSOR 1
The COMPRESSOR 1 LED illuminates solid to indicate the 1st stage compressor is energized.
REV VALVE ’O’
The REV VALVE ‘O’ LED will illuminate solid to indicate that the reversing valve on a heat pump
system is being energized to the COOL position. The LED will be out during heating mode on a
heat pump.
The W2 LED illuminates solid to indicate 2nd stage of HEATING is energized in a conventional
HVAC system. Or the W2 LED illuminates solid to indicate the 2nd stage of Auxiliary or Backup heat
is energized in a heat pump system. (4th stage heat) Also illuminates during Emergency mode.
EMERGENCY
The EMERGENCY LED illuminates solid to indicate all stages of Auxiliary, Backup, and Standby Heat
have been energized and Compressor 1 and 2 have been locked out. This is done in response to a
demand from any Heat Pump thermostat connected to any zone. It can also be activated via the
On-board Emergency switch. When Emergency mode is activated, the W1 & W2 LED’s will also
illuminate.
GROUND FAULT
The GROUND FAULT LED illuminates when the Circuit Breaker Trips due to an electrical short in
the thermostat field wiring or possibly in the main module damper field wiring. The electrical short
must be located and repaired before the circuit breaker can be reset to normal.
GREEN
RED
GREEN
GREEN
GREEN
YELLOW
RED
RED
RED
GREEN
GREEN
GREEN
GREEN
ORANGE
YELLOW
ORANGE
RED
RED
RAS
The RAS LIMIT LED illuminates solid to indicate that the Return Temperature has exceeded the chosen
set point. LED will blink rapidly to indicate a malfunctioning Return Air Sensor.
RED
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