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T7100D,E,F MICROELECTRONIC COMMERCIAL THERMOSTATS AND Q7100A,C,D SUBBASES
68-0163—3
15
Fig. 22. Typical hookup of Q7100C1073 in three-stage heat, one-stage cool heat pump system.
Includes remote temperature sensor, remote setback timer.
TROUBLESHOOTING GUIDE
EQUIPMENT
MONITOR 2
L1
(HOT)
L2
M15325A
FAN
RELAY
D
OE W3 Y2
COOL
CHANGEOVER
VALVE
HEAT
CHANGEOVER
VALVE
SUBBASE
2
XB G
EM. HT.
RELAY
R
TD
REMOTE
TEMPERATURE
SENSOR
AUX. HT.
RELAY
Y1
T
COMPRESSOR
CONTACTOR 2
CAUTION: EQUIPMENT DAMAGE. CAN BURN OUT THERMOSTAT. DO NOT CONNECT POWER TO THE D TERMINAL.
DO NOT PARALLEL SEVERAL THERMOSTATS FROM A SINGLE SOURCE UNLESS ISOLATION RELAYS ARE USED.
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
SELECT MODELS HAVE LEDS.
X4 NEEDS TO BE JUMPERED TO TERMINAL X.
1
2
REMOTE
SETBACK
TIMER
1
3
COMPRESSOR
CONTACTOR 1
X3
EQUIPMENT
MONITOR 1
X1X4
4
3
4
(continued)
Symptom Possible Cause Action
Display does not
come on.
Thermostat is not being
powered.
• Check that X terminal is connected to the system transformer.
• Check for 24 Vac between X and R or RH terminals.
— If missing 24 Vac:
— Check if the circuit breaker is tripped; if so, reset the circuit
breaker.
— Check if the system fuse is blown; if so, replace the fuse.
— Check if the power switch on the HVAC equipment is in the
Off position; if so, set to the On position.
— Check wiring between thermostat and HVAC equipment and
replace any broken wires and tighten any loose connections.
— If 24 Vac is present, proceed with troubleshooting.
Temperature
display is incorrect.
Room temperature display has
been reconfigured.
Enter Installer Setup 37 and reconfigure the display.
Thermostat is configured for °F
or °C display.
Enter Installer Setup 14 and reconfigure the display.
Bad thermostat location. Relocate the thermostat.
Display shows two dashes and
a degree sign.
Installer Setup 22 is set for remote sensing and the sensor is missing or
the circuit is open or shorted.
Temperature
settings will not
change. (Example:
Cannot set the
heating higher or
the cooling lower.)
The upper or lower temperature
limits were reached.
Check the temperature setpoints:
• Heating limits are 40 to 90°F (7 to 31°C).
• Cooling limits are 45 to 99°F (9 to 37°C).
Heating does not
come on.
No power to the thermostat. • Check that X terminal is connected to the system transformer.
• Check for 24 Vac between X and R or RH terminals.
— If missing 24 Vac:
— Check if the circuit breaker is tripped; if so, reset the circuit
breaker.
— Check if the system fuse is blown; if so, replace the fuse.
— Check if the system switch at the equipment is in the Off
position; if so, set to On position.
— Check wiring between thermostat and HVAC equipment and
replace any broken wires and tighten any loose connections.
— If 24 Vac is present, proceed with troubleshooting.