Defrost Control; S F T /T A M A; Superheat Can Be Determined As Follows; Otor - Goodman GPH1524M41 Installation Manual

Since the temperature of the refrigerant in the outdoor coil on the
heating cycle is generally below freezing point, frost forms on the
surfaces of the outdoor coil under certain weather conditions of
temperature and relative humidity. Therefore, it is necessary to re-
verse the flow of the refrigerant to provide hot gas in the outdoor
coil to melt the frost accumulation. This is accomplished by revers-
ing the heat pump to the cooling cycle. At the same time, the out-
door fan stops to hasten the temperature rise of the outdoor coil
and lessen the time required for defrosting. The indoor blower
continues to run and the supplementary heaters are energized.
D C
EFROST ONTROL
During operation the power to the circuit board is controlled by a
temperature sensor, which is clamped to a feeder tube entering the
outdoor coil. Defrost timing periods of 30, 60 and 90 minutes may
be selected by connecting the circuit board jumper to 30, 60 and 90
respectively. Accumulation of time for the timing period selected
starts when the sensor closes (approximately 34°F), and when
the wall thermostat calls for heat. At the end of the timing period,
the unit's defrost cycle will be initiated provided the sensor re-
mains closed. When the sensor opens (approximately 60°F), the
defrost cycle is terminated and the timing period is reset. If the
defrost cycle is not terminated due to the sensor temperature, a
ten minute override interrupts the unit's defrost period.
TEST
JUMPER WIRE
90 A
60
30
C Y
S F T
UGGESTED IELD ESTING
1. Run unit in the heating mode (room thermostat calling for
heat).
2. Check unit for proper charge. Note: Bands of frost on the
condenser coil indicate low refrigerant charge.
3. Shut off power to unit.
4. Disconnect outdoor fan by removing the purple lead wire
from "DF2" on defrost control. On 460V units, remove the
red wire on DF2.
5. Restart unit and allow frost to accumulate.
6. After a few minutes of operation, the unit's defrost
thermostat should close. To verify this, check for 24 volts
between "DFT" and "C" on board. If the temperature at the
thermostat is less than 28° F and the thermostat is open,
replace the unit's defrost thermostat, as it is defective.
7. When the unit's defrost thermostat has closed, short the
test pins on the defrost board until the reversing valve
shifts, indicating defrost. This should take up to 21
seconds depending on what timing period the control is
set on. After defrost initiation, the short must instantly be
removed or the unit's defrost period will only last 2.3
seconds.
8. After the unit's defrost thermostat has terminated, check
the defrost thermostat for 24 volts between "DFT" and "C".
The reading should indicate 0 volts (open sensor).
9. Shut off power to unit.
10.Replace outdoor fan motor lead to terminal "DF2" on defrost
board and turn on power.
W2 R R DFT
/T S
ROUBLE HOOTING
A M
IRFLOW EASUREMENT AND
After reviewing Duct Work section, proceed with airflow measure-
ments and adjustments. The unit blower curves (see Specification
Sheets) are based on external static pressure (ESP per in/wc). The
duct openings on the unit are considered internal static pressure.
As long as ESP is maintained, the unit will deliver the proper air up
to the maximum static pressure listed for the CFM required by the
application (i.e. home, building, etc.)
In general, 400 CFM per ton of cooling capacity is a rule of thumb.
Some applications depending on the sensible and latent capacity
requirements may need only 350 CFM or up to 425 CFM per ton.
Check condition space load requirements (from load calculations)
and equipment expanded ratings data to match CFM and capacity.
After unit is set and duct work completed, verify the ESP with a
1-inch inclined manometer with pitot tubes or a Magnahelic gauge
and confirm CFM to blower curves in the Specification Sheets.
NOTE: Never run CFM below 350 CFM per ton, evaporator freezing
or poor unit performance is possible.
S T A
PEED AP DJUSTMENTS
X-13 Motor
Adjust the CFM by changing the 24V low voltage lead at the speed
terminal block on the motor. (T1-Low Speed, T2 and T3-Medium
DF2
Speed, T4 and T5-High Speed).
Note: Factory set T1 (G, fan), T2 (cool/Hi cool), T3 (W2 electric
DF1 heat), T4 and T5 reserved for high static (cool/Hi cool) and W2.
GPH1348M41 and GPH1360M41 low cool Y1 will run at G speed.
See Specification Sheet for GPH model series for CFM vs ESP
tables.

SUPERHEAT CAN BE DETERMINED AS FOLLOWS:

1. Read suction pressure. Determine Saturated Suction
Temperature from tables or pressure gauge saturated
temperature scale (R-410A).
2. Read suction line temperature.
3. Use the following formula:
10
A
DJUSTMENT
F I B M
OR NDOOR LOWER

OTOR