Back seating service valves are not equipped with Schrader
valves. Fully back seat (counter clockwise) valve stem before
removing gage port cap.
Do not vent refrigerant to atmosphere. Recover during system
repair or final unit disposal.
Follow these steps to properly start up the system:
1. Fully back seat (open) liquid and vapor service valves.
2. Unit is shipped with valve stem(s) front seated (closed) and
caps installed. Replace stem caps after system is opened to
refrigerant flow (back seated). Replace caps finger-tight and
tighten with wrench an additional 1/12 turn. Use a backup
wrench on valve body flats to prevent distortion of sheet
metal.
3. Close electrical disconnects to energize system.
4. Set room thermostat at desired temperature. Be sure set point
is below indoor ambient temperature.
5. Set room thermostat to HEAT or COOL and fan control to ON
or AUTO mode, as desired. Operate unit for 15 minutes.
Check system refrigerant charge.
SEQUENCE OF OPERATION
NOTE: Defrost control board is equipped with a 5-minute lock-
out timer which may be initiated upon an interruption of power.
With power supplied to indoor and outdoor units, transformer is
energized.
Cooling
On a call for cooling, thermostat makes circuits R-O, R-Y, and
R-G. Circuit R-O energizes reversing valve, switching it to cooling
position. Circuit R-Y energizes contactor, starting outdoor fan
motor and compressor circuit. R-G energizes indoor unit blower
relay, starting indoor blower motor on high speed.
When thermostat is satisfied, contacts R-Y open, de-energizing the
contactor and blower relay. Compressor and motors should stop.
NOTE: If indoor unit is equipped with a time-delay relay circuit,
the blower runs an additional 90 sec to increase system efficiency.
Heating
On a call for heating, thermostat makes circuits R-Y and R-G.
Circuit R-Y energizes contactor, starting outdoor fan motor and
compressor. Circuit R-G energizes indoor blower relay, starting
blower motor on high speed.
Should temperature in the dwelling continue to fall, R-W2 is made
through second-stage room thermostat. Circuit R-W2 energizes
supplemental electric heat. If outdoor temperature falls below
setting of outdoor thermostat (field-installed option), contacts
close to bring on an additional bank of supplemental electric heat.
When thermostat is satisfied, its contacts open, de-energizing
contactor and sequencer. All heaters and motors should stop after
all fan off delays.
A97413
LEGEND
24-V FACTORY WIRING
24-V FIELD WIRING
FIELD SPLICE CONNECTION
OUTDOOR THERMOSTAT
EMERGENCY HEAT RELAY
SUPPLEMENTAL HEAT RELAY
SHR
EHR
ODT
WIRING DIAGRAM NOTES:
1. CARRIER THERMOSTAT WIRING DIAGRAMS ARE ONLY ACCURATE FOR MODEL NUMBERS TSTAT_______.
2. WIRING MUST CONFORM TO NEC OR LOCAL CODES.
3. ALL UNITS ARE EQUIPPED WITH PRESSURE SWITCHES, TEMPERATURE SWITCH, AND 5-MINUTE COMPRESSOR
CYCLE PROTECTION. CONNECT 24-V FIELD WIRING TO FACTORY-PROVIDED STRIPPED LEADS.
4. THERMOSTATS ARE FACTORY CONFIGURED WITH 5-MINUTE COMPRESSOR CYCLE PROTECTION AND 4 CYCLES
PER HR LIMIT. SEE THERMOSTAT INSTALLATION INSTRUCTIONS FOR DETAILS.
5. TO STAGE ELECTRIC RESISTANCE HEAT, CONSULT OUTDOOR THERMOSTAT INSTALLATION INSTRUCTIONS.
6. UNDERLINED LETTER ON DUAL TERMINAL INDICATES ITS USAGE.
FOR EXAMPLE: O/W2 MEANS O
O/W2 MEANS W2
7. OUTDOOR TEMPERATURE SENSOR MUST BE ATTACHED IN ALL DUAL FUEL INSTALLATIONS.
JUMPER WIRE BETWEEN O/W2 AND L THERMOSTAT TERMINALS MUST BE PRESENT.
8. Y1 AND O CONNECTIONS TO 2-STAGE FURNACES MAY NOT EXIST OR MAY ONLY BE A WIRE RATHER THAN A
SCREW TERMINAL.
12
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