Honeywell T7351 Installation Instructions Manual page 11

Fig. 9. Typical hookup of T7350F2010 in three-stage heat and three-stage cool conventional system
TROUBLESHOOTING GUIDE (TABLE 7)
Symptom
Display will not Thermostat is not being powered.
come on.
Temperature Thermostat is configured for °F or
display is °C display.
incorrect.
Bad thermostat location.
Display shows three dashes and a
degree sign (all systems shut
down).
Temperature Upper or lower temperature limits
settings will not were reached.
change.
(Example:
Occupied setpoint temperature
Cannot set
range stops were configured.
heating higher or
Keypad is locked. When a locked
cooling lower.)
key is pressed, LOCKED appears
momentarily on the LCD.
Room Remote temperature sensing is not
temperature is working.
out of control.
T7770 REMOTE SENSOR
9 8 7 6 5 4 3 2 1
SUBBASE
T5 T6 T7 T4 T3
HS HC HP
HUMIDITY
SENSOR
L2
1 2
L1
(HOT)
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
ENSURE TRANSFORMER IS SIZED TO HANDLE THE LOAD.
2
3
HEAT/COOL SYSTEMS WITH ONE TRANSFORMER REQUIRE THE FACTORY-INSTALLED JUMPER.
4 USE ECONOMIZER INSTRUCTIONS FOR INSTALLATION DIRECTIONS.
Table 7. Troubleshooting Information.
Possible Cause
T7351 COMMERCIAL PROGRAMMABLE THERMOSTAT
4
OUTDOOR
AIR
ECONOMIZER
SENSOR
DISCHARGE
HEAT
AIR
RELAY 3
SENSOR
OS OS AS AS AUX W3/Y4 Y3
M M X RH RC AUX
3
MOTION
SENSOR
with one transformer.
Check that X terminal is connected to the system transformer.
Check for 24 Vac between X and RH terminals.
If missing 24 Vac:
• Check if circuit breaker is tripped; if so, reset circuit breaker.
• Check if system fuse is blown; if so, replace fuse.
• Check if the HVAC equipment power switch is in the Off
position; if so, set to the On position.
• Check wiring between thermostat and HVAC equipment.
Replace broken wires and tighten loose connections.
If 24 Vac is present, proceed with troubleshooting.
Press both Run Schedule and Copy, then reconfigure the
display.
Relocate the thermostat.
T7351 is set for remote sensing and sensor is missing or circuit
is either open or shorted.
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)
Check setpoint stops. If necessary, reconfigure the stop(s).
Press both Run Schedule and Copy, then change keypad lock
level.
Check all remote sensors.
11
COMPRESSOR
CONTACTOR 2
HEAT
RELAY 2
W2 Y2
W1 Y1 G
COMPRESSOR
CONTACTOR 3
HEAT
FAN
RELAY 1
RELAY
COMPRESSOR
CONTACTOR 1
M25319
Action
62-0258