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3 − Potential Relay K31 (Start)
All single-phase units with a
reciprocating compressor
,
use a potential relay which controls the operation of the
starting circuit. The potential relay is located inside the
unit control box (see figure 4). The relay is normally closed
when contactor K1 is de-energized. When K1 energizes,
the compressor immediately begins start-up. K31
remains closed during compressor start-up and start
capacitor C7 remains in the circuit. When the compressor
reaches approximately 75% of its speed, K31 is
energized. When K1 energizes, the contacts open and
start capacitor C7 is taken out of the circuit. Potential
relays are critically matched to the specific compressor
applied.
4 − Start Capacitor C7
All single-phase units with a
reciprocating compressor
,
use a start capacitor (C7). C7 is located inside the unit
control box (see figure 4). C7 is wired in parallel with the
compressor side of the dual capacitor.See table 2 for
startcapacitor ratings.
Unit
MFD
VAC
HP29 START CAPACITOR RATING (C7)
HP29−211/261/311
HP29−461/511/651
HP29−411
189−227
330
145−175
330
216
176−216
HP29−018/024
145−175
330
TABLE 2
5 − Run Capacitor C1
The fan in all three−phase units uses a single-phase
permanent split capacitor motor. A single capacitor C1 is used
for the fan motor. C1 is located inside the unit control box (see
figure 3). Table 3 shows the ratings of C1.
Unit
MFD
VAC
HP29 RUN CAPACITOR RATING (C1)
HP29−413/463/513
7.5
370
5
370
HP29-653
HP29−036
5
370
HP29−042/048/060
7.5
370
TABLE 3
6 − Outdoor Fan Relay K10
Outdoor fan relay K10 is used on all G" and J" voltage
units to energize the outdoor fan B4. The relay is located
in the control box and is a single-pole double-throw
relay. See figure 3. K10 is energized by the indoor
thermostat terminal Y1 (24V). When K10 is energized, a
set of N.O. contacts closes to energize the outdoor fan.
7 − Compressor Contactor K1
The compressor is energized by a contactor located in the
control box. See figures 3, 4, and 5. Single−pole and
two-pole contactors are used in single-phase units and
three-pole contactors are used in three-phase units. See
wiring diagrams for specific unit. K1 is energized by the indoor
thermostat terminal Y1 (24V). Single−phase HP29 units are not
equipped with a 24V transformer. All 24 VAC controls are
powered by the indoor unit. Refer to unit wiring diagram. "J"
voltage units only are equipped with a 24V transformer. See
figure 3.
DANGER
Electric Shock Hazard.
May cause injury or death.
Disconnect all remote electrical power
supplies berore opening unit panel. Unit
may have multiple power supplies.
Some units are equipped with single−
pole contactors. When unit is equipped
with a single−pole contactor, line voltage
is present at all components (even when
unit is not in operation).
8 − Defrost System HP29
Unit built prior to April 2002
The HP29 defrost system includes two components: a
defrost thermostat and a defrost control.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect electronic
components. Take precautions during unit instal-
lation and service to protect the unit’s electronic
controls. Precautions will help to avoid control
exposure to electrostatic discharge by putting
the unit, the control and the technician at the
same electrostatic potential. Neutralize electro-
static charge by touching hand and all tools on an
unpainted unit surface before performing any
service procedure.
Defrost Thermostat S6
The defrost thermostat is mounted on the liquid line
between the check/expansion valve and the distributor.
HP29−211 through −653 have a defrost setting of 35
_
F
(2
_
C) and HP29−018 through −060 have a defrost setting
of 42
_
F (5.5
_
C). When defrost thermostat senses the
setpoint or cooler, its contacts close and send a signal to
the defrost control board to start the defrost timing. It
also terminates defrost when the liquid line warms up to
70
_
F (21
_
C).
Defrost Control CMC1
The defrost control board in
t
he HP29 series units has the
combined functions of a time/temperature defrost control,
defrost relay, diagnostic LEDs and field connection terminal
strip.
The control provides automatic switching from normal
heating operation to defrost mode and back. During
compressor cycle (room thermostat demand cyle), if the
O" input is not on and the defrost thermostat is closed, the
control accumulates compressor run times at 30-, 60- or
90-minute field adjustable intervals. If the defrost
thermostat remains closed when the accumulated
compressor run time ends, the defrost relay is energized
and defrost begins.
