Carrier COMFORT 25HCS - Manual (Page 5)

5
Install Electrical Accessories
Refer to the individual instructions packaged with kits or
accessories when installing.
Start--Up
CAUTION
!
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal
injury.
Wear safety glasses, protective clothing, and gloves when
handling refrigerant and observe the following:
S
Front seating service valves are equipped with Schrader valves.
CAUTION
!
ENVIRONMENTAL HAZARD
Failure to follow this caution may result in environmental
damage.
Federal regulations require that you do not vent refrigerant to
the atmosphere. Recover during system repair or final unit
disposal.
CAUTION
!
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this caution may result in personal injury,
equipment damage or improper operation.
S
Do not overcharge system with refrigerant.
S Do not operate unit in a vacuum or at negative pressure.
S Do not disable low pressure switch in scroll compressor
applications.
S Compressor dome temperatures may be hot.
Follow these steps to properly start up system:
1. After system is evacuated, fully 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.
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.
24 VAC HOT R
C
W2
Y
G
R
C
RVS COOLING
C
W2
HP THERMOSTAT
TYPICAL
FAN COIL
HEAT
PUMP
G
O
E
W2
E
W3
R
Y
24 VAC COM
HEAT STAGE 2
COOL/HEAT
STAGE 1
INDOOR FAN
EMERGENCY
HEAT
O
*
*
*
IF AVAILABLE *
LEGEND
24-V FACTORY WIRING
24-V FIELD WIRING
FIELD SPLICE CONNECTION
OUTDOOR THERMOSTAT
EMERGENCY HEAT RELAY
SUPPLEMENTAL HEAT RELAY SHR
EHR
ODT
A02325 / A97413
Fig. 8 -- Generic Wiring Diagrams
(See Thermostat Installation Instructions
for specific unit combinations)
Sequence of Operation
NOTE: Defrost control board is equipped with 5 minute lockout
timer that is initiated upon any interruption of power.
Turn on power 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 sends low voltage through the
safeties and energizes the T1 terminal on the circuit board. If the
compressor has been off for 5 minutes, or power has not been
cycled for 5 minutes, the OF2 relay and T2 terminal will energize.
This will close the contactor, and start the outdoor fan motor and
compressor.
When the cycle is complete, R--Y is turned off, stopping the
compressor and outdoor fan. The 5 minute time guard begins
counting. Compressor will not come on again until this delay
expires. In the event of a power interruption, the time guard will
not allow another cycle for 5 minutes.
NOTE: If the indoor blower off delay is enabled, it will run up to
an additional 90 seconds to increase system efficiency.
Heating
On a call for heating, thermostat makes circuits R--Y and R--G.
Circuit R--Y sends low voltage through the safeties and energizes
the T1 terminal on the circuit board. T1 energizes the defrost logic
circuit. If the compressor has been off for 5 minutes, or power
has not been cycled for 5 minutes, the OF2 relay and T2 terminal
will energize. This will close the contactor, start the outdoor fan
motor and compressor.
When the cycle is complete, R--Y is turned off , stopping the
compressor and outdoor fan. The 5 minute time guard begins
counting. Compressor will not come on again until this time delay
expires. In the event of a power interruption, the time guard will
not allow another cycle for 5 minutes.
25H
C
S