Carrier 38BYC Installation And Start-Up Instructions Manual page 6

4, Set room them_ostat to desired temperature, Be sure set point
is below indoor=ambient temperature
5, Set room them_ostat to HEAT or COOL and fire control to ON
o1" A'LTO mode, as desired. Operate unit fbr 15 minutes
Check system=refi'igerant charge.
SEQUEN(E OF OPERATION
NOTE: Defi'ost=control board may be equipped with 5-minute
lockout timer that may be initiated upon any interruption of power.
With power supplied to indoor and outdoor units, trans*brmer is
energized.
( OOLING
On a call _br cooling, them_ostat makes circuits R=O, R=¥, and
R-G. Circuit R=O energizes reversing valve, switching it to cooling
position. Circuit R=Y energizes contactor, starting outdoor=_im
motor and compressor circuit. R-G energizes indoor unit=blower
relay, starting indoor=blower motor on high speed.
When thermostat is satisfied, its contacts 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.
HP THERMOSTAT
m
24 VAC HOT F_
24 VAC COM
HEAT STAGE E_
COOL/HEAT
STAGE 1
INDOOR FAN
RVS COOLINC E_
EMERGENCY
HEAT
outdoor temperature fi_lls below setting of outdoor thermostat
(field=installed option), contacts close to complete circuit and bring
on second bank of supplemental electric heat.
When thermostat is satisfied, its contacts open, de-energizing
contactor and relay. All heaters and motors should stop.
DEFROST
The defi'ost contlol is a time/temperature control which includes a
field=selectable (quick=connects located at board edge) time period
between deflost cycles (30, 60, or 90 minutes), factoQ set at 90
minutes.
The electronic timer and defrost cycle start only when contactor is
energized and defi'ost flaermostat is closed.
Defi'ost mode is identical to cooling mode except that outdoor=fan
motor stops and second-stage heat is turned on to continue
wamaing conditioned space.
To initiate defi'ost, the defiost thermostat must be closed. This can
be accomplished as %llows:
1. Turn off power to outdoor unit.
2. Disconnect outdoor=Jim motor lead [i'om OF2 on control
board. (See Fig. 10.) Tape lead to prevent grounding.
TYPICAL HEAT
FAN COIL PUMP
,a--D ---q4S
* IF AVAILABLE
Fig. g--Generic Wiring Diagram
(See Thermostat Insta{iation Instructions for wiring specific unit combinations.)
LEGEND
24-V FACTORY WIRING
24-V FIELDWIRING
FIELDSPLICECONNECTION
ODT
OUTDOOR THERMOSTAT
EMERGENCY HEAT RELAY
SUPPLEMENTAL HEAT RELAY
A02325
A97413
HEATING
On a call for heating, thermostat makes circuits R=¥ and R-G
(ircuit R=¥ energizes contactor, starting outdoor=_im motor and
compressor. Circuit R-G energizes indoor-blower relay, starting
blower motor on high speed.
Should temperature continue to £fll, R=W2 is made through
second-stage room=them_ostat bulb, Circuit R-W2 energizes a
relay, bringing on first bank of supplemental electric heat and
providing electrical potential to second heater relay (if used) If
3, Restart unit in heating mode, allowing[i'ost to accumulate on
outdoor coil.
4. After a few minutes in heating mode, liquid-line temperature
should drop below closing point of defiost thermostat (ap=
proximately 30°F).
5. Short between speed=up terminals with a flat=blade screw-
&iver. (See Fig. 10) This reduces the timing sequence to
1/256th of original time. (See Table 3.)