Specifications

TROUBLESHOOTING PROCEDURES
The most common operating problems and types of errors
associated with the monitor thermostat are:
• Operating Problems. No display or flashing displays occur
when the monitor thermostat is not receiving rated power
or has miswired connections.
• Equipment Operating Problems. The monitor thermostat
does not select a system mode, does not energize the as-
sociated unit, or does not energize the second stage of the
unit.
• Hardware Failure (HF) Errors. These errors occur when
the monitor thermostat detects a problem with one of its
own components or associated device.
• Storage Failure (SF) Errors. These errors occur when the
monitor thermostat detects and replaces faulty data con-
tained within memory with factory selected default
values.
• System Errors (SE). These errors occur when the monitor
thermostat detects a system or zone operating problem.
Operating problems other than those listed above may be
related to the network operation.
General Operating Problems
NO DISPLAY — If the monitor thermostat display remains
blank after 24 vac power has been applied to the damper
actuator or relay pack, it is an indication that power is not
reaching the monitor thermostat.
At the damper actuator or single zone relay pack, check
that adequate power is being supplied from the power trans-
former. Acceptable voltage range is 21 to 30 vac.
The VA requirements are:
• 25 VA for a damper actuator and unit control relay pack.
• 25 VA for a single zone unit control relay pack.
Check the wiring between the 24 vac transformer and the
damper actuator or replace the transformer as necessary.
At the monitor thermostat wiring connector board, with
the monitor thermostat connected, check for approximately
10 vdc (steady) across the red and white wires from the damper
actuator.
Check the continuity of the 5 conductor wire running be-
tween the monitor thermostat wiring connector board and
the damper actuator.
Check that the monitor thermostat ribbon cable is prop-
erly seated in the wiring connector board. Disconnect, then
reconnect the ribbon cable from the connector board. If the
monitor thermostat display remains blank after the ribbon
cable is reconnected, use the ribbon cable wiring diagram in
the Monitor Thermostat Wiring section to check the monitor
thermostat wiring connector block and ribbon cable. Re-
place the wiring block or monitor thermostat if required.
At the damper actuator, with the monitor thermostat con-
nected, check for approximately 10 vdc (steady) across the
white and red wires to the monitor thermostat. If faulty, re-
place the damper actuator circuit board.
BLINKING DISPLAY — If the monitor thermostat display
blinks on and off, it is an indication the monitor thermostat
is continuously going through the power-up sequence and
cannot enter normal operating mode.
Check for any of the following conditions that would cause
the display to blink or constantly display four zeros:
• Low voltage from the 24 vac (10 VA for the single zone
relay pack) transformer. Acceptable voltage range is 22 to
30 vac.
• Unsteady 10 vdc across the red and white wires from the
damper actuator.
• The yellow or blue wire from the damper actuator or single
zone relay pack to the monitor thermostat wiring connec-
tor board is broken or disconnected.
• The monitor thermostat ribbon cable is improperly in-
stalled or defective.
• The monitor thermostat wiring connector board is defec-
tive. Refer to the Monitor Thermostat Wiring section for
ribbon cable and wiring connector block troubleshooting
information.
• The monitor thermostat, damper actuator, or single zone
relay pack is defective.
BLINKING HEAT OR COOL ANNUNCIATOR — If the
HEAT or COOL annunciator of the monitor thermostat dis-
play continuously blinks, it is an indication that the monitor
thermostat has detected that one of the High/Low Tempera-
ture Limits has been exceeded.
The monitor thermostat uses information from the supply
air temperature sensor, the associated zone controller(s) sup-
ply air temperature sensor(s), the associated bypass control-
ler supply air temperature sensor, and the DX coil tempera-
ture sensor for maintaining limits.
To return the blinking display to normal:
1. The display will return to normal when the supply air tem-
perature returns to within the limits of the current system
operating mode. Refer to page 33 for more information.
2. If the monitor thermostat does not utilize a DX coil sen-
sor, but the DX Coil Temperature Sensor option has been
configured to ON, the annunciator will blink. Reconfig-
ure the DX Coil Sensor option.
3. Check the monitor thermostat supply air temperature sen-
sor or DX coil temperature sensor to see if sensor is wired
incorrectly or defective.
4. Check all associated zone controller supply-air tempera-
ture sensors to see if sensors are wired incorrectly or
defective.
Equipment Operation Problems — The monitor ther-
mostat is designed to energize constant volume heating
and cooling equipment to satisfy the system comfort
requirements.
The monitor thermostat has three system configurations:
VVTt Monitor, Monitor Only, and Construction. The moni-
tor thermostat uses different criteria for analyzing the sys-
tem needs to make heating or cooling decisions (system mode).
When the monitor thermostat fails to pick a system mode,
or fails to energize the heating or cooling equipment when
expected, the problem usually involves the configurable op-
tions of the monitor thermostat.
If the monitor thermostat selects a system mode, but the
heating or cooling equipment fails to energize, the problem
may be with the damper or relay pack.
MONITOR THERMOSTAT FAILS TO SELECT SYSTEM
MODE — When the monitor thermostat fails to select a sys-
tem mode, check the items that influence the monitor ther-
mostat to select system mode.
1. The reference zone (zone with the greatest demand) must
be 1.5° F or more from set point.
2. The monitor thermostat system switches (FAN, COOL,
HEAT) must be set to AUTO or ON to operate.
3. If the outdoor temperature is below the Cooling Tem-
perature Lockout Set Point or above the Heating Tem-
perature Lockout Set Point, the monitor thermostat will
not enter into cooling or heating modes.
4. Ensure that the monitor thermostat Heating And Cooling
Time Guard has had time to expire. If the Time Guard
Between Modes option (category 4, option 2) has been
configured ON, the system will not operate until Time
Guard has expired. Time Guard delay occurs after power
up, reset, or system mode has been released. Length of
the Time Guard varies depending on the system mode and
operation.
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