short defrost cycle will be observed (actual length is dependent
upon the selected Quiet Shift position). When Quiet Shift switch is
in ON position, the length of defrost is 1 minute (30 sec
compressor off period followed by 30 sec of defrost with com-
pressor operation). On return to heating operation, compressor will
again turn off for an additional 30 sec and the fan for 40 sec. When
the Quiet Shift is in OFF position, only a brief 30 sec cycle will be
observed.
If it is desirable to observe a complete defrost in warmer weather,
the thermostat must be closed as follows:
1. Turn off power to outdoor unit.
2. Disconnect outdoor fan motor lead from OF2 on control board
(See Fig. 12.) Tape 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/-1°C).
NOTE:
Unit will remain in defrost until defrost thermostat
reopens at approximately 80°F (26.7°C) coil temperature at liquid
line or remainder of defrost cycle time.
5. Turn off power to outdoor and reconnect fan motor lead to
OF2 on control board after above forced defrost cycle.
Step 14—Check Charge
UNIT CHARGE
Factory charge is shown on unit rating plate. To check charge in
cooling mode, refer to Cooling Only Procedure. To check charge
in heating mode, refer to Heating Check Chart Procedure.
COOLING ONLY PROCEDURE
NOTE:
If superheat or subcooling charging conditions are not
favorable, charge must be weighed in accordance with unit rating
plate ± 0.6 oz/ft of 3/8-in. (56g/m of 9.5 mm) liquid line above or
below 15 ft (7.6 m) respectively.
EXAMPLE:
To calculate additional charge required for a 10 m line set:
10 m - 7.6 m = 2.4 m X 56 g/m = 134.4 g of additional charge
The following procedure is valid when indoor airflow is within ±
21 percent of its rated CFM.
1. Operate unit a minimum of 10 minutes before checking
charge.
2. Measure suction pressure by attaching an accurate gage to
suction valve service port.
3. Measure suction temperature by attaching an accurate ther-
mistor type or electronic thermometer to suction line near
service valve.
4. Measure outdoor air dry bulb temperature with thermometer.
5. Measure indoor air (entering indoor coil) wet bulb temperature
with a sling psychrometer.
6. Refer to Table 4. Find outdoor temperature and evaporator
entering air web bulb temperature. At this intersection, note
superheat.
7. Refer to Table 5. Find superheat temperature located in item 6
and suction pressure. At this intersection, note suction line
temperature.
8. If a unit has a higher suction line temperature than charted
temperature, add refrigerant until charted temperature is
reached.
9. If unit has a lower suction line temperature than charted
temperature, reclaim refrigerant until charted temperature is
reached.
10. When adding refrigerant, charge in liquid form into suction
service port using a flow-restricting device.
11. If outdoor air temperature or pressure at suction valve
changes, charge to new suction line temperature indicated on
chart.
HEATING CHECK CHART PROCEDURE
To check system operation during heating cycle, refer to the Heat
Pump Pressure chart label on outdoor unit. This chart indicates
whether a correct relationship exists between system operating
pressure and air temperature entering indoor and outdoor units. If
pressure and temperature do not match on chart, system refrigerant
charge my not be correct. Do not use chart to adjust refrigerant
charge.
Fig. 12—Defrost Control
A99442
OF2
CESO130076–00
OF1
ON
Q
UIET
SHIFT
120
30
60
60
30
90
INTER
V
AL
TIMER
OFF
P3
DFT
O R
W
2
Y C
T2 C C O
DFT
T1
Y
P1
J1
SPEEDUP
Speedup
Pins
Defrost interval
DIP switches
Quiet
Shift
8
