NOTE: If the phasing is incorrect, the contactor will not be
energized. To correct the phasing, interchange any 2 of the 3
power connections on the field side.
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.
Heating
On a call for heating, thermostat makes circuits R-Y and R-G. If
phasing is correct, 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 continue to fall, R-W2 is made through
second-stage room thermostat. Circuit R-W2 energizes relays,
bringing on supplemental electric heat. If outdoor thermostat is
used (field-installed option), only the first bank will be energized.
Remaining bank of supplemental electric heat will be energized
when outdoor temperature falls below outdoor thermostat setting.
When thermostat is satisfied, its contacts open, de-energizing
contactor and relays. All heaters and motors should stop.
Defrost
The defrost control is a time/temperature control which includes a
field-selectable (quick-connects located at board edge) time period
between defrost cycles (30, 50, or 90 minutes), factory set at 90
minutes.
Defrost mode is identical to cooling mode except that outdoor-fan
motor stops and second-stage heat is turned on to continue
warming conditioned space.
Initially the defrost cycle timer starts when the contactor is
energized and a 24v signal is present on the T1 terminal. Then the
defrost cycle begins when the cycle timer times out (30, 50, 90
min) and the defrost thermostat is closed.
To initiate defrost, the defrost thermostat must be closed. This can
be accomplished as follows:
1. Turn off power to outdoor unit.
2. Disconnect outdoor-fan motor lead from OF2 on control
board. (See Fig. .) Tape lead to prevent grounding.
3. Restart unit in heating mode, allowing frost to accumulate on
outdoor coil.
4. After a few minutes in heating mode, liquid-line temperature
should drop below closing point of defrost thermostat (ap-
proximately 30°F).
5. Short between speed-up terminals with a flat-bladed screw-
driver. (See Fig. 9.) This reduces the timing sequence to
1/256th of original time. (See Table 3.)
6. When you hear reversing valve change position, remove
screwdriver immediately; otherwise, control will terminate
normal 10-minute defrost cycle in approximately 2 sec.
Fig. 8—Phase-Monitor Control
Table 2—Phase-Monitor LED Indicators
LED STATUS
OFF
No call for compressor
operation
FLASHING Reversed phase
ON Normal
A00010
Fig. 9—Defrost Control
Table 3—Defrost Control Speedup-Timing
Sequence
PARAMETER
MINIMUM
(MINUTES)
MAXIMUM
(MINUTES)
SPEEDUP
(NOMINAL)
30–minute cycle 27 33 7 sec
50–minute cycle 45 55 12 sec
90–minute cycle 81 99 21 sec
10–minute cycle 9 11 2 sec
5 minutes 4.5 5.5 1 sec
A02001
R8
OF1
K1
O1
R21
C2
R6
H9C1
C US
®
R14
R13
D13
R7
C4
C10
JW2
JW1
D3
C16
C7
R28
D6
JW3
C13
R4
R1
R2
R3
R11
R5
R26
D1
D2
D10
A29
R9
D4
C19
C9
C1
C5
K2
OF2
CEBD430524-01A 5501A
P2
1
Y
T1 C C O
O
DFT
SPEEDUP
P1
1
J1
1
P3
1
J2
30 50 90
W1
R20
1
HK32EA001
C17
U1
1
U3
R
W2
Y
C
6
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