Carrier 33CS 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. 533-384 Printed in U.S.A. Form 33CS-44SI Pg 1 105 8-01 Replaces: 33CS-13SI
Book 1 4
Tab 11a 13a
Installation and Operating Instructions
Part Number 33CS071-01
CONTENTS
Page
SAFETY CONSIDERATIONS ......................1
GENERAL ........................................ 1
INSTALLATION ..................................1-5
Select Thermostat Location ......................1
Install Thermostat................................2
Heat Pump Configuration ........................2
Configure Advanced Setup.......................2
Install Accessories ...............................5
Sensor Calibration ...............................5
Check Thermostat Operation..................... 5
Final Checklist ...................................5
OPERATION.................................... 5-7
Mode Button Operation .......................... 5
Fan Button .......................................5
Emergency Heat Button ..........................5
Backlight Button ................................. 5
Reset Filter Button ...............................5
Override Button ..................................6
Electric Heat .....................................6
Two-Stage Operation ............................. 6
Emergency Heat ................................. 6
Remote Temperature Sensor .....................6
Keypad Lock .....................................6
Dry Contact Switch/External Control .............6
10-Watt Resistor .................................6
TROUBLESHOOTING............................. 8
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
hazard which could result in personal injury or death. CAU-
TION is used to identify unsafe practices which would result in
minor personal injury or property damage.
GENERAL
The commercial, non-programmable thermostats are wall-
mounted, low-voltage thermostats which maintain room tem-
perature by controlling the operation of an HVAC (Heating,
Ventilation, and Air Conditioning) system. Separate heating
and cooling set points and auto-changeover capability allow
flexibility. Dry contacts are available to control the thermostat
to occupied and unoccupied set points from an external device
for energy savings.
Batteries are not required. During power interruption the in-
ternal NEVERLOST™ memory stores the thermostat configu-
ration for an unlimited amount of time.
The thermostat can be configured to accept several different
equipment configurations, including heat pump operation.
NOTE: The thermostat is not factory-configured for use in heat
pump applications. The advanced setup must be performed to
configure the thermostat for use with heat pump units.
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.
33CS
Commercial Non-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.
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 two 3/16-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. 2-4 and Table 1.
9. Push excess wiring into wall. Seal hole in wall to prevent
drafts.
10. Reattach thermostat cover to 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). The following terminals are avail-
able: R (+ 24 v), W1/O/B (first stage heat or reversing
valve), Y1 (first stage cooling), G (fan relay), C (com-
mon), Y2 (second stage cooling), and W2 (second stage
heating).
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.
NOTE: Some large commercial rooftop heat pump units
(50HJQ,TJQ,EJQ) must be configured with Advanced Setup
Step 3 (Heat Pump Operation) set to OFF. Refer to the base
unit instructions for more information.
Table 1 — Thermostat Wiring Terminations
*Used on Heat Pump applications only.
Configure Advanced Setup — To enter into the ad-
vanced setup screens of the thermostat, press the Mode and
Backlight 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 17 Advanced Setup Steps. See Table 2. Press the
Backlight button at any time to exit the Advanced Setup mode.
UNOCCUPIED COOLING AND HEATING SET POINTS
(Steps 1 and 2) — When the thermostat is used in conjunction
with an external device wired to the dry contacts, the thermo-
stat is placed in unoccupied mode when the contacts open or
close (depending on the configuration of advanced setup
Step 9). The thermostat will control cooling and heating to the
Unoccupied Cooling and Heating Set Points.
The Unoccupied Cooling Set Point is configured in Step 1.
The acceptable range of values is 35 to 99 F. The configuration
can also be set to OF (does not allow unoccupied cooling). Af-
ter the desired temperature has been configured, press the
Mode button to continue to Step 2.
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.
EXISTING
WIRE
DESIGNATION
FUNCTION TERMINAL
CONNECTION
GorF Fan G
Y1,Y,orC Cooling Y1
W1,W,orH Heating W1/O/B
Rh,R,M,Vr,orA Power (24 v) R
CCommon C
O/B Reversing Valve W1/O/B*
Y2 Second Stage Cooling Y2
W2 Second Stage Heating W2
RS+5 Remote Sensor (5 vdc) RS+5
RS Remote Sensor Signal RS
RS G Remote Sensor Ground RS G
CK1 Dry Contact Switch 1 CK1
CK2 Dry Contact Switch 2 CK2
Fig. 1 — Thermostat Mounting
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105
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3
The Unoccupied Heating Set Point is configured in Step 2.
The acceptable range of values is 35 to 99 F. The configuration
can also be set to OF (does not allow unoccupied heating).
After the desired temperature has been configured, press the
Mode button to continue to Step 3.
HEAT PUMP CONFIGURATION (Steps 3 and 4) — 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 OFF.
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:Step4willappearonlyifStep3issettoON.Step5
will appear only if Step 3 is set to OFF.
ELECTRIC HEAT CONFIGURATION (Step 5) — Step 5 is
used to configure the thermostat for electric heat. The variable
can be configured ON or OFF. The default is OFF.
NOTE:Step5willappearonlyifStep3issettoOFF.
DEADBAND (Step 6) — 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 7) — The min-
imum difference between heating and cooling set points can be
user-configured. The range is from 0 to 6 degrees. The default
W2
TYPICAL
UNIT
L
C
G
Y1
E
O
W1
R
Y2
24 VAC COMMON
FAN RELAY
COMPRESSOR RELAY
1st STAGE HEAT CIRCUIT
24 VAC RETURN
2nd STAGE HEAT CIRCUIT
W2 Y2 RW1 Y1 GC
THERMOSTAT
B
O
W2
TYPICAL
UNIT
L
C
G
Y1
E
O
W1
R
Y2
24 VAC COMMON
FAN RELAY
COMPRESSOR RELAY
1st STAGE HEAT CIRCUIT
24 VAC RETURN
2nd STAGE COMPRESSOR RELAY
2nd STAGE HEAT CIRCUIT
W2 Y2 RW1 Y1 GC
THERMOSTAT
B
O
LEGEND
W2 — Second-Stage Heat
Y2 — Second-Stage Compressor
RS2 — Second Remote Sensor (Not Used)
RS+5 — +5 vdc
RS1 — Remote Sensor
RS GND — Ground
W1/O/B — First-Stage Heat or Reversing Valve
Y1 — First-Stage Compressor
G—Fan
W3/ECO — Economizer (Not Used)
CK1 — Dry Contact
CK2 — Dry Contact Ground
R—24 vac Transformer
C—24 vac Transformer Common
Fig. 2 — Thermostat Wiring
Fig. 3 — Typical Wiring (Single-Stage Cooling Units
and Two-Stage Heat Units)
Fig. 4 — Typical Wiring (Two-Stage Cooling Units
and Two-Stage Heat Units)
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→
→
105
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4
is 2 degrees. The minimum difference is enforced during
Autochangeover operation.
CYCLES PER HOUR LIMIT (Step 8) — 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.
DRY CONTACT CONFIGURATION (Step 9) — The Dry
Contact configuration is used to set the thermostat dry contacts
to normally open or normally closed. This should be set to
match the configuration of the external device (if present).
If the configuration is set to normally open, the thermostat
will enter Unoccupied mode when the contacts close. If the
configuration is set to normally closed, the thermostat will en-
ter Unoccupied mode when the contacts open. The default is
normally open.
SERVICE FILTER (Steps 10 and 11) — Step 10 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 Advanced Setup Step 10
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. The
set point is adjusted in intervals of 50 hours. Set the variable to
0 to disable this function. The default is 500 hours.
SOFT START (Step 12) — The soft start is used when multi-
ple units are used in an application. The soft start staggers the
start-up times of the units in the event of power loss and restart.
Each unit should be assigned a unit ID number. The 30-second
delay time is multiplied by the unit ID number to get the total
soft start delay time for each unit. For example, if the unit ID
number is 10, set the Soft Start function to 10, the start-up
delay time is 30 seconds x 10 = 300 seconds (5 minutes). The
range is 0 to 99 (ID numbers). A value of 0 disables the func-
tion. The default is 0 (ID number).
FAHRENHEIT/CELSIUS OPERATION (Step 13) — 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.”
SENSOR TYPE (Step 14) — The Sensor Type setting con-
figures the thermostat for use with a remote room sensor, out-
side temperature sensor, or duct temperature sensor. The Sen-
sor Type can be set to Yes or No.
When the Sensor Type is set to Yes, the outside or duct tem-
perature can be viewed by pressing and holding the Mode but-
ton for 2 seconds. If a sensor has not been installed, no temper-
ature will be displayed.
When the Sensor Type is set to No, the thermostat will de-
tect and use an installed sensor as a remote temperature sensor
to control thermostat operation. If a sensor has not been in-
stalled, the thermostat will use its internal temperature sensor.
SECURITY LEVEL (Steps 15 to 17) — 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 16
and 17. When the security level is set to “2,” the set point range
is limited by the settings of Steps 16 and 17 and the thermostat
operation mode cannot be changed. When the security level is
set to “3,” the set point range is limited by the settings of Steps
16 and 17, the thermostat operation mode cannot be changed,
and set point changes are prohibited. The default is 0.
Security Maximum Heat Set Point (Step 16) —IftheSecu-
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 17) — 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).
Table 2 — Advanced Set Up Configuration
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 8 to “d”
or “dl” unless specifically recommended for the application.
STEP DESCRIPTION RANGE DEFAULT
1Unoccupied Cooling Set Point 35 - 99 F / OF 85 F
2Unoccupied Heating Set Point 35 - 75 F / OF 55 F
3Heat Pump Off/On Off
4Reversing Valve Polarity O / B O
5Electric Heat Off/On Off
6Deadband 1 - 6 degrees 2
7Forced Minimum Temperature Difference 0 - 6 degrees 2
8Cycles per Hour d, d1, 2 - 6 6
9Dry Contact Switch Normally Open /
Normally Closed
Normally
Open
10 Reset Service Filter Icon — —
11 Service Filter Run Time 0-1950 hrs 500 hrs
12 Soft Start 0 - 99 0
13 Temperature Units F / C F
14 Sensor Type Yes / No No
15 Security Level 0 - 3 0
16 Maximum Allowable Heat Set Point 35 - 99 F (1- 37 C) 80 F (27 C)
17 Minimum Allowable Cooling Set Point 35 - 99 F (1 - 37 C) 65 F (18 C)
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105

5
Install Accessories — The following accessories can
be used with this thermostat:
• remote temperature sensor (33CSSEN-WB)
• outdoor temperature sensor (33CSSEN-01)
• duct temperature sensor (33CSSEN-DS)
• Add-a-Wire™ accessory (33CSACC-AW)
Refer to the accessory installation instructions for more
information.
REMOTE TEMPERATURE SENSOR — A remote temper-
ature sensor may be provided to read the temperature from a
space. If a remote temperature sensor is connected, the thermo-
stat will ignore the reading of its internal sensor. When the ther-
mostat is using a reading from a remote sensor, the degree sym-
bol above the temperature reading will blink.
When installing a remote sensor, do not run wiring in the
same conduit as the HVAC equipment control wires, fire alarm
wiring, or other high voltage wiring. Do not use the building
metalwork as a ground. Use only unshielded wire.
NOTE: Sensors can only be averaged when using a wireless
remote sensor (33CSRFS-RC/RE).
OUTDOOR TEMPERATURE SENSOR — An outdoor tem-
perature sensor may be provided to read the outside tempera-
ture. The thermostat will not control to the outside temperature
sensor. Outside temperature can be viewed by pressing and
holding the Mode button for 2 seconds.
NOTE: Advanced Setup Step 14 must be configured to Yes in
order to view outside temperature.
DUCT TEMPERATURE SENSOR — A duct temperature
sensor may be provided to either view the duct temperature or
to control to duct temperature (based on the setting of Ad-
vanced Setup Step 14). If Advanced Setup Step 14 is set to Yes,
then the duct temperature sensor reading can only be viewed
and the duct sensor is not used to control the thermostat. Press
and hold the Mode button for 2 seconds to view duct tempera-
ture. If Advanced Setup Step 14 is set to No, then the duct tem-
perature would control thermostat operation.
ADD-A-WIRE — The Add-A-Wire accessory is used to re-
pair a broken wire on a thermostat or to add an extra terminal
for cooling or heat pump operation.
Sensor Calibration — Every thermostat is factory cali-
brated. Under normal circumstances there will never be a need
to re-calibrate the thermostat. If re-calibration 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.
Check Thermostat Operation — To check thermo-
stat operation, perform the following procedure:
1. Press the Mode button repeatedly until the Heat icon ap-
pears on the display. The thermostat is now in Heating
mode.
2. 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. The red indicator
light should be lit.
3. Press the Mode button repeatedly until the Cool icon ap-
pears 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. The green indicator
light should be lit.
5. Press the Mode button repeatedly until the Off icon ap-
pears. Press the Fan button until the display reads Fan On.
The fan should energize.
6. If heating, cooling, or fan do not work, check wiring and
consult Troubleshooting section.
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
Mode Button Operation — The Mode button selects
the operating mode of the thermostat. 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 heating set point). If COOL is
selected, the thermostat will only enter Cooling mode (if the
room temperature is above the cooling 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.
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.
Fan Button — The Fan button is used to configure fan op-
eration. Fan operation can be set to Fan On or Auto (no icon
displayed).
When the fan is set to Fan On, the fan will run continuously
for better air circulation.
NOTE: If the thermostat is in the Unoccupied or OFF modes,
the fan will run only during heating or cooling.
When the fan is set to Auto (no icon displayed), the fan will
only energize during heating or cooling operation.
Emergency Heat Button — Emergency heat is avail-
able for heat pump applications. To turn on emergency heat,
press the Emergency Heat button. 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 com-
pressor). To exit emergency heat, press the Emergency Heat
button. During emergency heat, only OFF and HEAT modes
are available.
Backlight Button — The Backlight button is used to
change the setting of the Backlight display. If the configuration
is set to Yes, the backlight will be lit continuously. If the config-
uration is set to No, the display will be lit only after a button is
pushed. The display will stay lit until action has ceased.
Reset Filter Button — The Reset Filter button is used to
reset the Service Filter icon display while in the Advanced Set-
up Configuration Step 10.
If the Reset Filter button is pressed, then the number of
hours of fan operation is displayed. To reset the filter hours to
zero, press the Fan button while the hours are displayed.

6
Override Button — If the thermostat is connected to a
dry contact and is in Unoccupied mode, a press of the Override
button will force the thermostat into the mode it was in before
Unoccupied began. For example, if the thermostat was in the
Cool mode before the dry contacts forced the thermostat into
Unoccupied mode, a press of the Override button will tempo-
rarily return the thermostat to the Cool mode for 30 minutes.
Each subsequent push of the Override button will add 30 addi-
tional minutes to the Override time, up to 4 hours. If the timer
displays 4:00 hours, the next press of the Override button
will zero out the Override timer, returning the thermostat to
Unoccupied mode.
When in Override mode, the Override icon and the mode
icon (Off, Heat, Cool, or Auto) appear on the display along
with the time remaining in Override mode.
During Override mode, the set points are adjustable provid-
ed the keypad is not locked.
NOTE: The Override button can only be used if the dry con-
tact is used to control an Occupied and Unoccupied schedule.
Electric Heat — When the Electric Heat option in the
Advanced Setup is set to ON, the thermostat will turn on the
fan immediately any time there is a heat demand. This feature
should only be used on first stage electric heating applications.
Do not use with gas heat.
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.
Emergency Heat — Emergency heat is available for
heat pump applications. To turn on emergency heat, press the
Emergency Heat button. 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 the Emergency Heat button.
During emergency heat, only OFF and HEAT modes are
available.
Remote Temperature Sensor — A remote tempera-
ture sensor is available to read the temperature from a space. If
a remote temperature sensor is connected, the thermostat will
ignore the reading of its internal sensor. When the thermostat is
using a reading from a remote sensor, the degree symbol above
the temperature reading will blink.
NOTE: Sensors can only be averaged when using a wireless
remote sensor (33CSRFS-RC/RE).
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.
Dry Contact Switch/External Control — A dry con-
tact switch is provided to allow an external device to force the
thermostat into or out of Unoccupied mode. The external de-
vice is wired to contacts CK1 and CK2. See Fig. 5.
NOTE: Twenty-four volt power is not required for CK1 and
CK2.
When using the auxiliary input or controlling multiple
HVAC units with a single thermostat, it is possible to encounter
transformer phasing problems that will interfere with thermo-
stat operation.
Connecting transformers that are not phased correctly may
result in a direct short, which could damage transformers and/
or the thermostat. Phasing problems are likely if the units share
a common ground with secondary grounded transformers.
To avoid this problem, if possible, phase all HVAC units to-
gether. If phasing is impractical, isolation relays may be used to
isolate the transformers. To isolate the auxiliary input, use a
separate transformer for the auxiliary control device (usually a
timeclock). Connect the device to an isolation relay coil. Con-
nect one set of isolated contacts to each thermostat at CK1 and
CK2.
To prevent phasing problems when controlling multiple
HVAC units with one thermostat, phase the HVAC units or use
isolation relays to isolate the unit transformers. One unit will be
connected directly to the thermostat and the unit will power the
thermostat. All other units will require one set of isolated con-
tacts for each of the following: Heat, Cool, Fan, and Reversing
Valve (if required).
Units that are phased will have the high voltage legs to the
24 VAC power transformer in common. This requires identify-
ing which terminals from the high voltage input lugs are pro-
viding power to the transformer. Do not assume that the same
terminals will always provide power to the transformer. For
each unit, check the unit wiring diagram. See Fig. 6.
SOFT START — When multiple thermostats are controlled
by the same external device, a Soft Start option can be used to
stagger the turn on times of the HVAC equipment. This feature
may cause a delay in operation after entering Unoccupied
mode.
10-Watt Resistor — A 10-watt, 270-ohm resistor is pro-
vided with the thermostat. This resistor should only be used in
applications where it is necessary to use 4 wires in a power-
stealing mode when the common wire (C) is not available. It is
recommended that a common wire be used whenever possible.
Refer to the Troubleshooting section for more information on
resistor use and wiring.
Determining proper phasing can be difficult without the
help of an electrician (especially across different building
transformers). Damage to equipment can result if phasing
is improperly done. The use of isolation relays is recom-
mended before attempting phasing.
Do not attempt to rewire equipment internally to phase
units. Damage to unit components may occur.
105
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7
110 VAC
TIMECLOCK
TRANSFORMER
ISOLATION
RELAY
COIL
THERMOSTAT
THERMOSTAT
THERMOSTAT
CK1
GND
CK1
GND
CK1
GND
LL
23
L1L1L3
L2
A
B
C
SITE
POWER
24 VAC
UNIT WITH
TRANSFORMER
ON L AND L3
2
24 VAC
UNIT WITH
TRANSFORMER
ON L AND L2
1
NOTE: Additional relays may be used. Relay coils must be connected in parallel.
Fig. 5 — Typical Dry Contact Switch Wiring
Fig. 6 — Example of Unit Phasing

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 533-384 Printed in U.S.A. Form 33CS-44SI Pg 8 105 8-01 Replaces: 33CS-13SI
Book 1 4
Tab 11a 13a
Copyright 2001 Carrier Corporation
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 message 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
temperature. Check for 24 vac at Y1 terminal with a load connected. 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 temperature. Check for 24 vac at W1/O/B terminal with a load connected.
If present, thermostat is operating correctly and problem is with wiring or equip-
ment. If 24 vac is not present, replace the thermostat.
When using 4 wires (R,G,W,Y), the cooling equip-
ment tries repeatedly to turn on, but cannot. At
times the display dims or disappears.
There is not enough power available. Connect a 270-ohm, 10-watt power
resistor at the air-conditioning equipment between terminals W and C
(non-heat pump applications only).
When using 4 wires (R,G,W,Y), the heating equip-
ment tries repeatedly to turn on, but cannot. At
times the display dims or disappears.
There is not enough power available. Connect a 270-ohm, 10-watt
power resistor at the air-conditioning equipment between terminals
Y and C (non-heat pump applications only).
When controlling a heat pump, heat comes on
during cooling cycle.
Configure thermostat for heat pump operation (Table 2, Step 3).
When calling for cooling, both heating and
cooling are energized.
The thermostat is configured for a heat pump. Configure the thermostat
for non-heat pump operation (Table 2, Step 3).
When controlling a commercial heat pump unit,
unit runs in reverse or heating is always on.
Commercial heat pumps require that Heat Pump Option on thermostat
is turned OFF.
The thermostat temperature displays rises to 99 F. There is not enough voltage to the thermostat. Check wiring and power supply.
The resistor labeled “L3” on the thermostat is burned
out and brown. Thermostat will not work.
The thermostat has been wired incorrectly and circuit board is burned out.
Thermostat must be replaced.
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