Carrier 38EV024320 - Manual (Page 14)

appear on the display. Press either of the right (“Heat”)
setpoint buttons to change the display to “OFF.” This is
the indication that the thermostat is now correctly set for
single-zone control. Now adjust the displayed number to
“2” by pressing the cool setpoint buttons; the lower one to
decrease the number, upper one to increase. Return the
rotary switch to position #0 and press any setpoint button
to display the normal setpoints.
Adjust Heating/Cooling Setpoints—The setpoints for both
heating and coohng can be easily adjusted by pressing the
setpoint buttons as shown.
Installer Adjustable_Fe Clock Option—Each
thermostat is equipped with a buüt-in instruction manual
which explains the various installer adjustable features and
how to set the time clock.
FoUow each page of the manual to configure the thermostat
based on the application. Always set the “Local Set-back
Control” to ON.
For single-zone control applications, the following features
wül have no effect on the thermostat operation and can be
disregarded at the time of installation:
#6—Duct Temperature Sensor Calibration
#7—Max Damper Position/Min Ventilation Position
#C—System Demand
#D—Communication Test -
#E—Supplemental Heat
Error Codes—3ie displayed as HF, SF, HP or AC followed
by a two digit number (ref. Fig. 20.) An HF or SF code
indicates a thermostat malfunction (see Thermostat Trou­
bleshooting, below). A HP or AC code indicates a system
diagnostic
malfunction (see System Troubleshooting,
Section 5).
Set-Back Feature—li the homeowner desires to use the set­
back feature, remove the “set-back override jumper” from
the connector board at the back of the thermostat.
Operation—When an “OFF” time occurs, the thermostat
displays the word “SETBACK” and the highest cooRng and
lowest heating setpoints. When an “ON” time occurs the
thermostat returns to the last setpoints that were displayed
before set-back.
Overriding Set-Back—During set-back the heating'or cool­
ing set-back Setpoint can be manually 'overridden by adjust­
ing the setpoint through the use of the setpoint buttons.
The setpoint selected becomes the new comfort setpoint
that the thermostat uses when the next “OÑ” time occurs.
When the set-back setpdiiit is overridden the comfort
setpoint chosen remains displayed until the next “OFF”
time occurs; unless the' user manually adjusts the setpoint
back to the set-back setpoint; ;
Programming Set-Back—Follow the built-in thermostat
instruction mandai (behind front cover) to program the ON/
OFF times for set-back operation (and for programming the
electronic time clock). ■ , - .
Set-Back Programming Tips—If it is desirable for a particu­
lar period to be in set back coiitinuóuály do not enter any
ON/OFF times for that period;
If it is desirable, for a particular period to be in the comfort
rnode continuoúsíy enter an ON time that is the same as an
OFF time.
Heating/Cooling Cycles—The thermostat should be set to
energize a heating cycle and a cooling cycle. Check to make
certain the 38EV or 38QV system operates properly.
“HEAT,” “COOL,” or “FAN” may be shown in the lower
left corner of the thermostat display depending on the sta­
tus of the system. The 38EV or 38QV system controls to
1.5-deg.F from setpoint in both heat and cool modes. It will
start-up at 1.5 deg.F from setpoint (minimum run time is 12
minutes), and cycle off based on rate of room temperature
change (ref. Fig. 20).
VVI-ll Thermostat Troubleshooting
Hardware Failures—HF-11 or HF-12. The thermostat is not
properly configured for single-zone control application.
Make certain that “OFF” is displayed when the rotary
switcMs set to position #1.
HF-14, HF-15, or HF-16. There is a failure in the electronic
circuitry on the thermostat. Replace the thermostat circuit
board.
HF-13. The thermostat room temperature sensor is reading
out of its normal range ... 30 to 180 F. (Ref. thermostat
instructions).
Check the room temperature sensor to make sure that it is
physically intact.
Attempt to calibrate the room temperature sensor by fol­
lowing the built-in instruction manual. If cahbration is not
possible, replace the thermostat circuit board.
Storage Failures—The thermostat continuously checks its
memory to make certain that stored information is valid. If
information is ever determined to be invalid an error code of
“SF” followed by a number is displayed.
When an “SF” error is displayed, the thermostat will also
use a safe, substitute value appropriate to the particular
code. (See instructions included with thermostat.)
To Clear An “SF” Error—FoUow the buUt-in thermostat
manual to find the correct rotary switch position and reset
the desired setting. Then return the rotary switch back to
position #0.
Time Clock—The time clock should be accurate to within 10
minutes per year. During a power faUure, the time wiU be
maintained for a minimum of 8 hours, after which it may be
necessary to reset the clock, (Ref. thermostat instructions).
If the clock is not keeping accurate time, m^e certain the
power has not been off for over 8 hours. If it has not, then
replace the thermostat.
Set-Back—If the thermostat never goes into set-back make
certain:
'
The set-back override jumper has been removed from the
connector board.
,
The thermostat hasn’t been programmed to be continuously
in the comfort mode.
The thermostat is set for the proper time of day.
If the thermostat never comes out of set-back make certain:
A set-back On/Off program has been entered.
The thermostat is set for the proper time of day.
STEPS System Troubleshooting
TABLE OF CONTENTS
Self-Diagnostics—Description
Diagnostic Error Codes Page
Error Codes 3, 4—Outdoor Coil, Suction
Thermistor Failure....................................................... .16-17
Error Code 5—Indoor Coil Thermistor FaUure.......... 18-19
Error Code 8—Locked Compressor Rotor................... 20-21
Error Code 9—Overcurrent Trip............................ .22-23
Error Code 10—Contactor Control FaUure................. 24-25