24 TEC1100 Series Thermostat Technical Bulletin
Zone temperature control problems, usually reported as occupant hot/cold
complaints, can have causes ranging from the building or mechanical
system to the control components. Table 15 helps locate the cause of zone
temperature control problems with TEC1100 Series thermostats.
Table 15: TEC1100 Series Thermostat Troubleshooting
Symptom Possible Cause Corrective Action
Supply voltage incorrect. Use a voltmeter to check the voltage between the 24 V and
24 V(c) terminals. Voltage should be between 20-30 VAC.
If voltage is less than 20 VAC, disconnect the thermostat
and check the voltage between 24 V and the other system
wires; see possible causes below. If voltage is greater than
30 VAC, troubleshoot the power source and replace the
thermostat.
System transformer weak
or overloaded.
Check and/or replace with a suitable 24 V transformer.
No display/faint
display
Thermostat damaged
because system voltage
was greater than 30 VAC.
Replace with new thermostat, and ensure new thermostat
is isolated from the system using suitable relays and a
transformer of the proper rating.
Keyboard
inoperative.
Keyboard is locked. Switch the keyboard DIP switch to the unlocked position.
Short cycle delay still in
progress
Wait 2 to 4 minutes for the equipment short cycle
protection to complete.
Thermostat does
not call for heat.
Thermostat setpoint is
satisfied.
Press Mode button until thermostat is in heat mode. Raise
the heating setpoint using the ∧ button.
Short cycle delay still in
progress
Wait 2 to 4 minutes for the equipment short cycle
protection to complete.
Thermostat does
not call for cooling.
Thermostat setpoint is
satisfied.
Lower the cooling setpoint using the ∨ button.
Fan failure Place a wire between Terminals R and G. Fan should turn
on. If it does not, troubleshoot the fan system. If fan contact
does not energize, replace the thermostat.
Fan does not turn
on with the system.
Plenum temperature switch
failure
In Heat mode with a separate plenum switch, the fan does
not turn on until the plenum is up to its preset temperature.
Replace the plenum switch.
“AC” is flashing in
the LCD.
20-30 VAC absent from
R and C terminals
Using a voltmeter, measure voltage between the 24 V and
24 V(c) terminals. If the reading is less than 20 VAC, check
system transformer. If the voltage is between 20 and
30 VAC, replace the thermostat.
LCD shows missing
or extra segments.
LCD failure Replace the unit.
-55 appears when
Outdoor button is
pushed.
The sensor wire is open
inside the outdoor/duct
sensor module.
Repair or replace the sensor element (SEN-500-604 or
SEN-500-605; see the SEN-500-2 and SEN-500-3 Outdoor
Air Temperature Sensors Product/Technical Bulletin
[LIT-216179] for more information).
“-- -- --” appears.
Miswired outdoor air sensor
or N2 override missing
Add the sensor. Check the N2 command.
Occupant
Hot/Cold
Complaints
Troubleshooting
Controls Group
507 E. Michigan Street
P.O. Box 423 www.johnsoncontrols.com
Milwaukee, WI 53201 Printed in U.S.A.
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