Carrier Aquazone 50QE900 User manual

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 535-00105 Printed in U.S.A. Form 50QE-4SI Pg 1 6-03 Replaces: New
Book 1 4
Ta b 5 a 5 a
Installation and Operating Instructions
Part Numbers 50QE900-220LA
CONTENTS
Page
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . 1
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Select Thermostat Location . . . . . . . . . . . . . . . . . . . . . . 1
Install Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Set Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Heat Pump Configuration . . . . . . . . . . . . . . . . . . . . . . . . 3
Configure Advanced Setup. . . . . . . . . . . . . . . . . . . . . . . 3
Program Thermostat Schedules. . . . . . . . . . . . . . . . . . 4
Calibrate Temperature Sensor. . . . . . . . . . . . . . . . . . . . 6
Light Sensor Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . 6
Check Thermostat Operation. . . . . . . . . . . . . . . . . . . . . 6
Final Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6,7
Auto-Changeover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Light-Activated Operation . . . . . . . . . . . . . . . . . . . . . . . . 6
Two-Stage Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Clock Backup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Fan Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Emergency Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Holiday Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Keypad Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SAFETY CONSIDERATIONS
Read and follow manufacturer instructions carefully. Fol-
low all local electrical codes during installation. All wiring
must conform to local and national electrical codes. Improper
wiring or installation may damage thermostat.
Recognize safety information. This is the safety alert sym-
bol . When the safety alert symbol is present on equipment
or in the instruction manual, be alert to the potential for person-
al injury.
Understand the signal words DANGER, WARNING, and
CAUTION. These words are used with the safety alert symbol.
DANGER identifies the most serious hazards which will result
in severe personal injury or death. WARNING signifies a haz-
ard which could result in personal injury or death. CAUTION
is used to identify unsafe practices which would result in minor
personal injury or property damage.
GENERAL
The 7-day, commercial, programmable thermostats are
wall-mounted, low-voltage thermostats which maintain room
temperature by controlling the operation of an HVAC (heating,
cooling and ventilation) system. Separate heating and cooling
set points and auto-changeover capability allow occupied and
unoccupied programming for energy savings.
All thermostats allow up to 4 time/temperature settings to
be programmed per 24-hour period. Each thermostat stores
programs for 7 independent days. Batteries are not required.
During power interruption the internal NEVERLOST™ mem-
ory stores programmed schedules for an unlimited time while
the clock continues to run for at least 48 hours.
The thermostat can be configured to accept several different
equipment configurations, and is provided for heat pump
operation.
A light sensor is provided on the thermostat for light activa-
tion. When the sensor detects light (the space is occupied), the
thermostat will enter Occupied 1 mode. If the room is dark, the
thermostat will follow its programmed schedule.
INSTALLATION
Select Thermostat Location — The thermostat should
be mounted:
• approximately 5 ft from the floor
• close to or in a frequently used room, preferably on an
inside partitioning wall
• on a section of wall without pipes or ductwork
• where temperature operating limits are within 41 to
104 F (5 to 40 C)
• where humidity operating range is within 0 to 95% rela-
tive humidity, non-condensing
The thermostat should NOT be mounted:
• close to a window, on an outside wall, or next to a door
leading to the outside
• where exposed to direct light and heat from a lamp, the
sun, a fireplace, or any other temperature-radiating
object which may cause a false reading
• close to or in direct airflow from supply registers or
return air grilles
• in areas with poor air circulation (such as behind a door
or in an alcove)
IMPORTANT: Read entire instructions before starting
the installation.
50QE900
Aquazone™ Water Source Heat Pump
Commercial Programmable Thermostat

2
Install Thermostat
1. Turn off all power to unit.
2. If an existing thermostat is being replaced:
a. Remove existing thermostat from the wall.
b. Disconnect wires from existing thermostat. Do not
allow wires to fall back into the wall. As each wire
is disconnected, record wire color and terminal
connection.
c. Discard or recycle old thermostat.
NOTE: Mercury is a hazardous waste and must be
disposed of properly.
3. Remove the thermostat cover from wall plate (mounting
base) to expose mounting holes. See Fig. 1. With the ther-
mostat facing forward, press the back plate on the left
hand side top corner to release the two prongs holding on
the cover. Pull off the cover when the prongs have been
disengaged.
4. Route thermostat wires through large hole in mounting
base. Remove outer sheath from wires for added flexibili-
ty. Standard solid or multi-conductor thermostat wire
should be used from the thermostat to the unit. Size and
length considerations are as follows: for a maximum
distance from unit of 36 ft, use 22 AWG (American
Wire Gage) wire; for a maximum distance from unit
of 100 ft, use 18 AWG wire.
5. Level mounting base against wall and mark wall through
the 2 mounting holes in base.
6. Drill two3/16-in. mounting holes in wall where marked.
7. Secure mounting base to wall with 2 screws and anchors
provided. Ensure all wires exit through hole in mounting
base.
8. Adjust wire length and routing to allow proper closure of
the thermostat. Strip each wire at the end no more than
1/4-in. to prevent adjacent wires from shorting together.
Match and connect wires to terminals on the thermostat.
See Fig. 2-5 and Table 1.
9. Push excess wiring into wall. Seal hole in wall to prevent
drafts.
10. Re-attach thermostat cover to back plate by aligning the
top two prongs of the back plate in the vertical groove of
the top cover and then snapping the cover onto the back
plate.
11. Turn on power to unit. The thermostat will receive power
from the unit. The thermostat will be powered by 24 v,
nominal (18 to 30 vac). Terminals R (+ 24 v), W1/O/B
(first stage heat or reversing valve), Y1 (first stage cool-
ing), G (fan relay), and C (common) will always be con-
nected. Some applications will use Y2 (second stage
cooling) or W2 (second stage heating).
Before installing thermostat, turn off all power to the unit.
There may be more than one power disconnect. Electrical
shock can cause injury or death.
Be careful not to drill into wiring in wall. Electrical shock
could result.
Improper wiring or installation may cause damage to the
thermostat. Check to ensure wiring is correct before pro-
ceeding with installation of unit.
Fig. 1 — Thermostat Mounting
LEGEND
W2 — Second-Stage
Heat
Y2 — Second-Stage
Compressor
RS2 — Not Used
RS+5 — Not Used
RS1 — Not Used
RS GND — Not Used
W1/O/B — First-Stage Heat or
Reversing Valve
Y1 — First-Stage Compressor
G—Fan
W3/ECO — Third-Stage Heat or
Economizer (Not Used)
CK1 — Not Used
CK2 — Not Used
R—24 vac Transformer
C—24 vac Transformer
Common
Fig. 2 — Thermostat Wiring

3
Table 1 — Thermostat Wiring Terminations
*Terminals W2 and Y2 may not be used in all applications.
†Used on Heat Pump applications only.
Set Clock — The Set Clock button allows the user to
change the time and day displayed on the thermostat. Press the
Set Clock button. The current time will blink on and off. Press
the UP ARROW and DOWN ARROW buttons until the cor-
rect time is shown. Hold down the buttons to quickly move
through the time display. The AM and PM annunciators will
automatically change. Hold down the Fan button while press-
ing UP ARROW or DOWN ARROW to change the time by
hours instead of minutes. To ensure the schedules are properly
followed, make sure that AM or PM is correct for the time cho-
sen. When the correct time is shown, press the Mode button to
modify the day of the week. The current day will blink on and
off. Press the UP ARROW and DOWN ARROW buttons until
the correct day is shown. Press the Set Clock button again to
exit the Set Time mode.
Heat Pump Configuration — To configure the ther-
mostat for heat pump operation, Advanced Setup Steps 3 (Heat
Pump Operation) and 4 (Reversing Valve Polarity) must be
configured correctly. See the Configure Advanced Setup sec-
tion for information on configuring these options.
Configure Advanced Setup — To enter the ad-
vanced setup screens of the thermostat, press the Mode and
Program buttons at the same time. The Advanced Setup Step
number is shown in the top right corner of the thermostat
screen. Use the Mode button to advance through the steps.
There are 14 Advanced Setup Steps. See Table 2. Press the
Program button at any time to exit the Advanced Setup mode.
NOTE: Advanced Setup Steps 1 and 2 are configured with the
Set Clock button, and are not accessed through the advanced
setup screens.
HEAT PUMP CONFIGURATION (Steps 3 and 4) —
The thermostat is provided from the factory in heat pump
mode. To set the thermostat for heat pump operation,
Advanced Setup Step 3 must be configured to ON. Use the UP
and DOWN ARROW buttons to configure the step. The
default is ON. Press the mode button to continue to Step 4.
Step 4 is used to set the reversing valve polarity for the heat
pump. The variable can be set to either ‘‘B’’ or ‘‘O.’’ Set the
reversing valve polarity to the correct value depending on the
application. The default is ‘‘O.’’
NOTE: Step 4 will appear only if Step 3 is set to ON.
Table 2 — Advanced Setup Configuration
*Accessed and configured through the Set Clock button.
EXISTING
WIRE
DESIGNATION
FUNCTION TERMINAL
CONNECTION
G or F Fan G
Y1, Y, or C Cooling Y1
W1, W, or H Heating W1-O-B
Rh, R, M, Vr, or A Power (24 v) R
CCommon C
O/B Reversing Valve W1-O-B†
Y2 Second Stage Cooling Y2*
W2 Second Stage Heating W2*
STEP DESCRIPTION RANGE DEFAULT
1* Time of Day 12:00 AM -
11:59 PM 12:00 AM
2* Day of the Week Sunday through
Saturday Monday
3Heat Pump Off/On On
4Reversing Valve
Polarity O/B O
5Deadband 1 - 6 degrees 2
6Forced Minimum
Temperature Difference 0 - 6 degrees 2
7Cycles per Hour d, d1, 2 - 6 6
8Thermoglow™
Backlight Off/On On
9Reset Service
Filter Icon ——
10 Service Filter
Run Time 0-1950 hrs 500 hrs
11 Temperature Units F/C F
12 Security Level 0 - 3 0
13 Maximum Allowable
Heat Set Point 35-99 F (1-37 C) 80 F (27 C)
14 Minimum Allowable
Cooling Set Point 35 -99 F (1-37 C) 65 F (18 C)
Thermostat
RR
CC
GG
YY
WW
OO
RC
G
Y1
Y2 W1
W2
O
24 vac common
24 vac return
Fan
Compressor
Compressor 2
Cooling
COMPLETE C1 COMPLETE C2
B
Thermostat
R
C
G
Y1
Y2
W1
O/W2
RC
G
Y1
Y2 W1
W2
O
24 vac common
24 vac return
Fan
Compressor 1
Compressor 2
Cooling
DELUXE D
B
Fig. 4 —Water Source Heat Pumps Equipped
with 2 Complete C Control Boards
for Two-Stage Operation
Fig. 5 —Water Source Heat Pumps Equipped
with Deluxe D Control Board(s)
for Single or Two Stage Operation
Thermostat
R
C
G
Y
W
O
RC
G
Y1
Y2 W1
W2
O
24 vac common
24 vac return
Fan
Compressor
Cooling
COMPLETE C
B
Fig. 3 —Water Source Heat Pumps Equipped
with One Complete C Control Board
for Single-Stage Operation

4
DEADBAND (Step 5) — The deadband is the difference in
temperature above the cooling set point or below the heating
set point that the thermostat will wait before turning on the first
stage of heating or cooling. For example, if the cooling set
point is 82 F (28 C) and the deadband is 2 degrees, the first
stage of cooling will not be energized until the temperature
reaches 84 F (30 C). The range of values is 1 to 6 degrees. The
default is 2 degrees.
SET POINT MINIMUM DIFFERENCE (Step 6) — The min-
imum difference between heating and cooling set points can be
user-configured. The range is from 0 to 6 degrees. The default
is 2 degrees. The minimum difference is enforced during Auto-
Changeover and Program On operation.
CYCLES PER HOUR LIMIT (Step 7) — The number of
times that heating or cooling can be energized per hour can be
configured. Set the variable to ‘‘d’’ for no limit. Set the variable
to ‘‘d1’’ to disable the 5-minute compressor lockout. The vari-
able can also be set from 2 to 6 cycles per hour. The default is
6 cycles per hour.
BACKLIGHT DISPLAY (Step 8) — The display backlight
can be set to ON (always on) or OFF (turn off 8 seconds after
usage). The default is ON.
SERVICE FILTER (Steps 9 and 10) — Step 9 allows the
user to reset the Service Filter counter to zero and remove the
‘‘SERVICE FILTER’’ icon (if displayed on the thermostat
screen). Press the FAN button while in Setup Step 9 and the
counter is reset to zero. Press the Mode button to adjust the
number of hours the blower will run before the ‘‘SERVICE
FILTER’’ icon is displayed. The range is 0 to 1950 hours. Set
the variable to 0 to disable this function. The default is
500 hours.
FAHRENHEIT/CELSIUS OPERATION (Step 11) — The
thermostat can be set to operate in Fahrenheit or Celsius de-
grees. Set the variable to ‘‘F’’ for Fahrenheit operation. Set the
variable to ‘‘C’’ for Celsius operation. The default is ‘‘F.’’
SECURITY LEVEL (Steps 12 to 14) — The Security Level
limits the actions that the user can perform at the thermostat.
There are 4 security levels. When the security level is set to
‘‘0,’’ no security will be in effect. When the security level is set
to ‘‘1,’’ the set point range is limited by the settings of Steps 13
and 14. When the security level is set to ‘‘2,’’ the set point
range is limited by the settings of Steps 13 and 14 and the Pro-
gram On mode is always in effect. When the security level is
set to ‘‘3,’’ the set point range is limited by the settings of
Steps 13 and 14, the Program On mode is always in effect, and
set point changes are prohibited. The default is 0.
Security Maximum Heat Set Point (Step 13) — If the Secu-
rity Level is not set to 0, the maximum heating set point will be
in effect. The user will not be allowed to set the heating set
point over the specified value. The range of values is 35 to 99 F
(1 to 37 C). The default is 80 F (27 C).
Security Minimum Cool Set Point (Step 14) — If the Securi-
ty Level is not set to 0, the minimum cooling set point will be
in effect. The user will not be allowed to set the cooling set
point below the specified value. The range of values is 35 to
99 F (1 to 37 C). The default is 65 F (18 C).
Program Thermostat Schedules —Before pro-
gramming the thermostat, plan the thermostat daily schedule.
The schedule is divided into 7 days (Monday through Sunday).
Each day has from 2 to 4 time periods (Occupied 1, Occupied
2, Occupied 3, Unoccupied) depending on the configuration of
the thermostat. Each occupied time period has a start time, stop
time, heating set point, and cooling set point. The unoccupied
time period has a heating set point and a cooling set point. The
unoccupied time period is active when ever an occupied time
period is not active. Fill in Table 3 as an aid to programming
the daily schedules.
NOTE: When the sensor detects light (the space is occupied),
the thermostat will enter Occupied 1 mode. If the room is dark,
the thermostat will follow its programmed schedule. The
Occupied 1 schedule should be turned OFF to keep the ther-
mostat from entering Occupied 1 while the room is unoccu-
pied. If the Occupied 1 schedule is turned ON, the thermostat
will enter Occupied 1 per the schedule regardless of light acti-
vation. The Occupied 1 set points are used as the heating and
cooling set points during light activation. The Unoccupied set
points should be used as non-work hour set points (before
8:00 AM and after 5:00 PM) when using light activation. For
times when the building is unoccupied during work hours
(Monday through Friday, 8:00 AM to 5:00 PM), the Occupied
2 schedule should be turned ON, and can be used for moderate
energy savings with set points of 80 F for cooling and 65 F for
heating.
PROGRAMMING MODE — To program the daily sched-
ules, perform the following procedure:
1. Enter programming mode by pressing the Program but-
ton. The Occupied 1 annunciator will appear on the ther-
mostat display. Use the UP ARROW and DOWN
ARROW buttons to set the maximum number of Occu-
pied periods for each day. The thermostat can be set to 1,
2, or 3. After the number of Occupied periods has been
selected, press the Mode button. See Fig. 6.
2. The cooling set point for Occupied 1 will be displayed.
Use the UP ARROW and DOWN ARROW buttons to
raise or lower the cooling set point until the desired tem-
perature is shown. The range of acceptable values is 35 to
99 F (1 to 37 C). Press the Mode button to continue. See
Fig. 6.
3. The heating set point for Occupied 1 will be displayed.
Use the UP ARROW and DOWN ARROW buttons to
raise or lower the heating set point until the desired tem-
perature is shown. The range of acceptable values is 35 to
99 F (1 to 37 C). Press the Mode button to continue. See
Fig. 6.
4. The cooling set point for Unoccupied will be displayed.
Use the UP ARROW and DOWN ARROW buttons to
raise or lower the cooling set point until the desired tem-
perature is shown. The range of acceptable values is 35 to
99 F (1 to 37 C) or ‘‘OF’’ (no unoccupied cooling). Press
the Mode button to continue.
Damage to compressor could result if 5-minute compressor
lockout is disabled or compressor is allowed unlimited
cycles. Do not set thermostat Advanced Setup Step 7 to
‘‘d’’ or ‘‘dl’’ unless specifically recommended for the
application.
Fig. 6 —Setting Occupied 1 Set Points

5
Table 3 —Daily Schedule Planner
NOTE: The cooling temperature set point must be higher than the heating temperature set point.
(The temperature difference may be changed in the advanced set up configuration.)
5. The heating set point for Unoccupied will be displayed.
Use the UP ARROW and DOWN ARROW buttons to
raise or lower the heating set point until the desired tem-
perature is shown. The range of acceptable values is 35 to
99 F (1 to 37 C) or ‘‘OF’’ (no unoccupied heating). Press
the Mode button to continue.
6. The day of the week will be shown. Use the UP ARROW
and DOWN ARROW buttons to change the day of the
week until the desired starting day is shown. Possible
choices are M (Monday) through S (Sunday). Press the
Mode button when the desired day is shown.
7. The Start Time for Occupied 1 will be displayed. Use the
UP ARROW and DOWN ARROW buttons to raise or
lower the time until the desired Start Time is shown.
Press the Mode button to continue. See Fig. 7.
8. The Stop Time for Occupied 1 will be displayed. Use the
UP ARROW and DOWN ARROW buttons to raise or
lower the time until the desired Stop Time is shown. Press
the Mode button to continue.
9. The On/Off icon will be displayed. Use the UP ARROW
to turn the Occupied 1 period ON for this day. Use the
DOWN ARROW to turn the Occupied 1 period OFF for
this day.
10. Repeat Steps 2 through 9 to program the remaining
schedule for Occupied periods 2 and 3.
11. The Copy command can be used to copy the previous
day’s schedule if the schedules are the same. The copy
command becomes available after all the occupied peri-
ods are programmed in a day. Use the UP ARROW to
change the copy command to YES. Use the DOWN
ARROW to change the copy command to NO. Press the
Mode button when the choice has been made. See Fig. 8.
If NO was selected, the schedule will automatically
change to the next day and the user must enter the occu-
pied and unoccupied schedules for that day.
NOTE: Occupied 1 schedule heating and cooling set
points are the same for each day. Occupied 2 and 3 set
points may be set to different values for each day of the
week.
If YES was selected, the schedule will be copied to the
next day. The schedule copy may be repeated until Sun-
day is reached. The Sunday schedule cannot be copied to
Monday.
12. After all the times and set points for each day have been
entered, press the Program button to exit Programming
mode.
DAY
OF THE
WEEK
SCHEDULE
Occupied 1 Occupied 2 Occupied 3 Unoccupied
Start / Stop / Heat / Cool Start / Stop / Heat / Cool Start / Stop / Heat / Cool Heat / Cool
Monday /// /// /// /
Tuesday /// /// /// /
Wednesday /// /// /// /
Thursday /// /// /// /
Friday /// /// /// /
Saturday /// /// /// /
Sunday /// /// /// /
Fig. 7 —Start Time Display
Fig. 8 —Copy Command Display

6
NOTE: The thermostat will continue to follow the schedule
until a new one is entered.
If only one occupied schedule is selected, the Occupied 2
and 3 schedules are skipped. If the start time is set later in the
day than the stop time, the program will run from midnight of
that day to the stop time and then from the start time to mid-
night. If the same start and stop times are programmed for an
occupancy schedule, the thermostat will be in Occupied mode
for 24 hours. If one occupied period starts or stops within
another occupied period, the lower numbered schedule has pri-
ority. For example, if schedule Occupied 3 is running for
24 hours and Occupied 2 schedule comes on from 1 to 3 PM,
the set points from Occupied 2 are in effect from 1 to 3 PM.
OVERRIDING THE SCHEDULE — The schedule can be
overridden by pressing the UP or DOWN ARROW buttons to
change the desired temperature. The thermostat will use the
new set point until the next scheduled time period starts.
Calibrate Temperature Sensor —Every thermo-
stat is factory calibrated. Under normal circumstances there
will never be a need to re-calibrate the thermostat. If recalibra-
tion must be done, perform the following procedure:
1. Hold down the Mode and Fan buttons for 5 seconds. All
of the icons on the display screen will appear. Release the
buttons. Press the UP and DOWN ARROW buttons
simultaneously.
2. Press the UP and DOWN ARROW buttons simulta-
neously again. The current temperature will be displayed.
3. Use an accurate thermometer to measure room tempera-
ture. Press the UP or DOWN ARROW buttons until the
number equals room temperature.
4. Press the Mode button to return to normal operation.
Light Sensor Adjustment —The light sensor is used
for light-activated operation. The sensor can be adjusted for a
variable degree of sensitivity. The sensitivity adjustment screw
is located on the inner cover of the thermostat, near the DOWN
ARROW button. Turning the screw clockwise increases the
sensitivity of the sensor to light. Turning the screw counter-
clockwise decreases the sensitivity of the sensor to light.
To check for correct sensitivity, place the thermostat in Pro-
gram On mode. The thermostat should be in Occupied 1 when
the lights are on. If the sensor does not enter Occupied 1 while
the lights are on, turn the screw clockwise until the Occupied 1
icon appears on the display. The thermostat should enter
Unoccupied mode when the lights are off. If the sensor does
not enter Unoccupied when the lights are turned off, turn the
screw counterclockwise until the Unoccupied icon appears on
the display.
Check Thermostat Operation —To check thermo-
stat operation, perform the following procedure:
1. Press the Mode button repeatedly until the Heat icon
appears on the display. The thermostat is now in Heating
mode.
2. Press the Fan button. The Fan Auto icon will appear on
the display screen. Press the UP ARROW button until the
heating set point is 10 F (6 C) higher than the current
room temperature. Heating and fan should be energized.
3. Press the Mode button repeatedly until the Cool icon
appears on the display. The thermostat is now in Cooling
mode.
4. Press the DOWN ARROW button until the cooling set
point is 10 F lower than the current room temperature.
Cooling and fan should be energized.
5. Press the Mode button repeatedly until the Off icon
appears. Press the Fan button until the display reads Fan
On. The fan should energize.
6. If heating, cooling, or fan operation do not work, check
wiring and consult Table 4.
Final Checklist
1. Put away tools and instruments. Clean up debris and
packaging.
2. Review Owner’s Guide with occupant or owner.
3. Leave the manuals with owner.
OPERATION
The Mode button selects the operating mode of the thermo-
stat. If OFF is selected, the thermostat will not enter Heating or
Cooling mode. If HEAT is selected, the thermostat will only
enter Heating mode (if the room temperature is below the heat-
ing set point). If COOL is selected, the thermostat will only
enter Cooling mode (if the room temperature is above the cool-
ing set point). If AUTO is selected, the thermostat will enter
Heating or Cooling mode based on the room temperature and
the heating and cooling set points. If PROGRAM ON is select-
ed, the stored schedule is enabled and the thermostat will fol-
low the Occupied and Unoccupied schedules stored in its
memory.
Auto-Changeover —When the thermostat mode is set
to AUTO, the thermostat will provide automatic changeover
from Heating to Cooling mode and Cooling to Heating mode
when required. The thermostat will automatically switch to
maintain the desired temperature setting. The thermostat does
not need to be manually changed from heating to cooling or
cooling to heating operation.
Light-Activated Operation —A light sensor is pro-
vided on the thermostat for light activation. The thermostat
must be in Program On mode for light activation to be initiated.
When the sensor detects light (the space is occupied), the ther-
mostat will enter Occupied 1 mode and heat or cool according
to the Occupied 1 set points. If the room is dark, the thermostat
will follow its programmed schedule.
NOTE: Light activation does not work in Holiday mode.
IMPORTANT: An external device should not be used
with the dry contact switch with light activated opera-
tion. The light sensor is wired to the dry contact switch.
Another device will cause conflicting signals to the ther-
mostat. The RED wire of the sensor is wired to CK1.
The BLACK wire of the sensor is wired to CK2.

7
Two-Stage Operation —The second stage of heat or
cool is turned on when the first stage has been on for a mini-
mum of 2 minutes and the temperature differential from the set
point is equal to or greater than the set point plus the deadband
plus 2 degrees.
Clock Backup —In the event of a power loss, the ther-
mostat will keep time for a minimum of 48 hours without
external power or batteries.
Fan Operation —If Fan On is selected, the fan will run
continuously during occupied schedule (except when Mode is
switched to OFF). The fan will be off during unoccupied
schedule except during heating or cooling operation.
If Fan On is not selected, the fan will only operate during
heating or cooling operation.
Emergency Heat —Emergency heat is available for
heat pump applications. To turn on emergency heat, press and
hold the Fan button. While holding the Fan button, press the
UP button for 2 seconds. An ‘‘EH’’ will be displayed. During
emergency heat, the fan will operate and the second stage of
heat will be energized (locking out the first stage compressor).
To exit emergency heat, press and hold the Fan button. While
holding the Fan button, press the UP button for 2 seconds. Dur-
ing emergency heat, only OFF and HEAT modes are available.
Holiday Mode —When the thermostat is in Holiday
mode, the thermostat will operate under Unoccupied set points.
To configure and activate the Holiday mode, press the Holiday
button. The ‘‘HOL’’ icon will be displayed along with the re-
maining days of Holiday mode operation. Press the UP or
DOWN ARROWS to select the number of days that the holi-
day schedule will be in effect. A value of 0 disables Holiday
mode. The duration can be set from 1 to 99 days. The thermo-
stat will enter Holiday mode on midnight of the next day after
the mode has been activated. Holiday mode will remain in
effect until midnight of the last configured day.
If the Holiday mode is in effect, the number of days remain-
ing will blink on and off and the ‘‘Unoccupied’’ icon will be
displayed. The Override button will be active during Holiday
mode.
To turn off the Holiday mode before the remaining config-
ured days have passed, press the Holiday button to enter into
the configuration mode. Press the DOWN ARROW to set the
number of days to zero. Holiday mode will be disabled.
Keypad Lock —To prevent unauthorized use of the ther-
mostat, the front panel buttons can be disabled. To disable or
lock the keypad, press and hold the Mode button. While hold-
ing down the Mode button, press the UP and DOWN ARROW
buttons simultaneously. The ‘‘Locked’’ icon will appear on the
display.
The thermostat is unlocked by performing the same proce-
dure. Press and hold the Mode button. While holding down the
Mode button, press the UP and DOWN ARROW buttons
simultaneously. The ‘‘Locked’’ icon will be removed from the
display.
TROUBLESHOOTING
Table 4 —Thermostat Troubleshooting
PROBLEM SOLUTION
Display on thermostat not illuminated. Check for 24 vac at the R terminal connection. Terminal R must be connected
for proper thermostat operation.
‘‘Service Filter’’ is displayed on thermostat. After the configured number of blower operating hours, the Service Filter mes-
sage will be displayed. This reminds the owner to replace the filter. Reset the
Service Filter feature to reset the blower operation timer to 0 hours.
Cooling will not energize. Select COOL mode. Decrease cooling set point to 10 degrees below room tem-
perature. Check for 24 vac at Y1 terminal. If present, thermostat is operating
correctly and problem is with wiring or equipment. If 24 vac is not present,
replace the thermostat. Check for Compressor Cycle per Hour Limit. Cooling
may be locked out.
Heating will not energize. Select HEAT mode. Increase heating set point to 10 degrees above room tem-
perature. Check for 24 vac at W1/O/B terminal. If present, thermostat is operat-
ing correctly and problem is with wiring or equipment. If 24 vac is not present,
replace the thermostat.
When controlling a heat pump, heat comes on
during cooling cycle.
Configure thermostat for heat pump operation (Table 2, Step 3).

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 535-00105 Printed in U.S.A. Form 50QE-4SI Pg 8 6-03 Replaces: New
Book 1 4
Ta b 5 a 5 a
Copyright 2003 Carrier Corporation