Lennox Diplomat 10HP12 Information page 3

A – Control Box (Figure 2)
10HP UNIT CONTROL BOX
START CAPACITOR
(C7)
DEFROST
RELAY (K4)
COMPRESSOR
CONTACTOR
(K1)
GROUNDING
LUG
FIGURE 2
A low voltage make up area is provided for thermostat
field wiring. Field thermostat wiring is made to color
coded pigtail connections as illustrated in figure 3.
THERMOSTAT WIRING IDENTIFICATION
RED
YELLOW
ORANGE
BEIGE
BLACK
FIGURE3
DANGER
Shock Hazard
All 10HP units use single-pole
contactors. One leg of compressor,
capacitor and outdoor fan are
connected to line voltage at all
times. Potential exists for electrical
shock resulting in injury or death.
Remove all power at disconnect
before servicing.
Can cause personal injury or death.
1 – Compressor Contactor K1
The compressor is energized by a contactor located in
the control box. See figure 2. Contactors are SPST in
single phase units and 3PST in three phase units. K1 is
energized by the indoor thermostat terminal Y (24V).
10HP units are not equipped with a line voltage to 24V
transformer. All 24 VAC controls are powered by the
indoor unit. Refer to unit wiring diagram.
DUAL CAPACITOR
(C12)
POTENTIAL
RELAY (K31)
DEFROST
CONTROL
CMC1
TIMED OFF
CONTROL (A4)
10HP60 ONLY
LOW VOLTAGE
MAKEUP AREA
24V (POWER) INPUT
TO OUTDOOR UNIT
(COMPRESSOR) INPUT
(REVERSING VALVE)
INPUT
(ELECTRIC HEAT)
DEFROST OUTPUT
(COMMON)
Page 3
2 – Dual Capacitor C12
The compressor and fan in 10HP units use permanent
split capacitor motors. The capacitor is located inside the
unit control box (see figure 2). A single "dual" capacitor
(C12) is used for both the fan motor and the compressor
(see unit wiring diagram). The fan side and the
compressor side of the capacitor have different MFD
ratings. See table 1 for dual capacitor ratings.
TABLE 1
10HP (C12) DUAL CAPACITOR RATING
Unit Terminal
FAN
10HP12
HERM
10HP18, 24 and FAN
HERM
30-2
FAN
10HP30-1 and 36
HERM
FAN
10HP36-4
HERM
FAN
10HP42
HERM
FAN
10HP48 and 60
HERM
3 – Potential Relay K31 (Start)
All 10HP units use a potential relay which controls the
operation of the starting circuit. The potential relay is
located inside the unit control box (see figure 2). The
relay is normally closed when contactor K2 is
de-energized. When K1 energizes, the compressor
immediately begins start-up. K31 remains closed
during compressor start-up and start capacitor
remains in the circuit. As the compressor gains speed,
K31 is energized. When K31 energizes, the contacts
open and start capacitor C7 is taken out of the circuit.
4 – Start Capacitor C7
All 10HP units use a start capacitor (C7). C7 is located
inside the unit control box (see figure 2). C7 is wired in
parallel with the compressor side of the dual
capacitor. See table 2 for start capacitor ratings.
TABLE 2
10HP START CAPACITOR RATING (C7)
Unit MFD
10HP12, 18 and 24 88–108
10HP30-1 and 36 88–108
10HP30-2 145–175
10HP36 (CAN) 88–108
10HP36-4
189-227
10HP42 and 48
10HP60 270-324
5 – Timed Off Control A4
A timed off control (A4) located in the control box is
used on 10HP60 units. See figure 2. The time delay is
electrically connected between thermostat terminal Y
and the compressor contactor. After cooling demand
has stopped, A4 begins counting for five minutes.
During the timing period, A4 disables the compressor
contactor. Thermostat demand will have no effect on
the unit.The unit cannot operate. After the delay, the
compressor contactor can be energized.
MFD VAC
5
25
5
35
370
5
45
5
40
10
40
440
10
60
C7
VAC
250
330
330
250
330
330