Troubleshooting - TCS UbiquiSTAT US4010 Product Manual

CHECKOUT AND

TROUBLESHOOTING

6.2 Troubleshooting
6.2.1 No Display
Remove cover and check for 24 VAC (22.8 to 27.6 VAC) on terminals labeled "+/- 24V". Replace the cover and check for
proper fit. Ensure the two internal board connectors snap in place. For more information on removing the cover, see
tion 1.
6.2.2 Fan Does Not Come On
The fan is on whenever the fan symbol on the home screen is animated. If the fan should be on, but the symbol is not
animated, check the fan and system modes. If the fan is off but the fan symbol is animated, check wiring. Connect a jump-
er between the "R" and "G" terminals to see if the fan comes on. If the fan comes on, the relay in the thermostat may be
faulty, or programming is incorrect. If the fan does not come on, check unit wiring to thermostat.
6.2.3 Heating or Cooling Does Not Come On
When the heating symbol is shown, at least one stage of heating is on, or an analog output is modulating for heat. When
the cooling symbol is shown, at least one stage of cooling is on, or an analog output is modulating for cool.
If the heating or cooling is not coming on, but the thermostat is calling for heat or cool respectively, this is most likely a
wiring issue. Check equipment wiring. Place a jumper across terminals "R" to "W1" and see if the heating comes on. Place
a jumper across terminals "R" to "Y1" and see if the cooling comes on. This is to check for a mechanical relay failure.
If you feel that the heating or cooling should be on, but the corresponding symbol is not visible, check the following:
• System Mode
• Heating and Cooling Setpoints
• Offsets and Differentials
• Room Temperature is above the Cooling Setpoint or below Heating Setpoint.
• Outdoor Air Lockout Status
• Discharge Air Limit Status
6.2.4 Wrong Temperature Display
The temperature displayed on the screen is the temperature that is used to control heating and cooling. If this temperature
reading is incorrect, the thermostat will not control properly.
If using the internal temperature sensor, check the calibration (see
If using a remote temperature sensor on the T1 terminals, check the room temperature source screen in the advanced
settings to verify programming (see
Section 4.5.2.2). Otherwise, use the system test mode screen to verify ohm readings of the temperature sensor (see
tion 4.5.2.10).
6.2.5 Thermostat is Overcooling or Underheating
Overcooling or underheating can occur if the thermostat top is placed too close to an air vent, where air is allowed to enter
the thermostat and cause erroneous temperature readings. To fix this problem the air stream from the vent will need to be
redirected, or the thermostat will need to be relocated, or a remote sensor could be used.
Overcooling can also happen if the thermostat is mounted in direct sunlight. In this case, the thermostat will need to be
relocated, or a remote sensor will need to be installed.
Overheating or undercooling can occur when air is allowed to flow into the thermostat from within the wall. If this occurs,
seal the wall where the wires enter the thermostat.
6.2.6 Service Status Symbol is Visible
This indicates the HVAC Equipment requires service. See
Section 4.5.2.3).If the temperature reading is only slightly off, check calibration (see
2800 Laura Ln, Middleton WI 53562 | 800.288.9383 Fax: 608.836.9044 | www.tcsbasys.com
Section 4.5.2.2).
Section 4.3 for more information on Service Status.
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