S-109B Heat Pump Heating Mode; Checking Expansion Valve Operation; Fixed Orifice Restriction Devices - Goodman ASX Service Instructions Manual

SERVICING
b. If subcooling is low and superheat is high, add
charge to raise subcooling to 5 to 7 ºF then check
superheat.
c. If subcooling and superheat are high, adjust TXV
valve to 7 to 9 ºF superheat, then check subcooling.
d. If subcooling is high and superheat is low, adjust
TXV valve to 7 to 9 ºF superheat and remove
charge to lower the subcooling to 5 to 7 ºF.
NOTE: Do NOT adjust the charge based on suction
pressure unless there is a gross undercharge.
4. Disconnect manifold set, installation is complete.
Subcooling Formula = Sat. Liquid Temp. - Liquid Line Temp.

S-109B HEAT PUMP HEATING MODE

Hot Gas Method
System charge can be checked in the heating mode by
measuring the hot discharge gas at the compressor.
1. Allow the system to operate at least 20 minutes.
2. Attach and insulate an electronic thermometer probe to
the vapor service valve (large line) at the base valve.
3. Operate the system for 10 minutes.
4. Using an accurate electronic thermometer, measure the
temperature of the discharge gas at the probe and the
outdoor ambient temperature.
5. The temperature measured on the vapor service valve line
should be equal to the outdoor ambient temperature plus
110°F (± 4°). For example, if the outdoor ambient tem-
perature is 45°F, then the temperature measured by the
thermometer probe at the vapor service valve line should
be 155°F for a system that is properly charged. If the
temperature measured by the thermometer probe is
higher than the outdoor ambient plus 110°F, the system
charge should be adjusted by adding refrigerant to lower
the temperature. If the temperature measured is lower
than the outdoor ambient plus 110°F, the system charge
should be adjusted by recovering charge to raise the
temperature
NOTE: When adjusting the charge in this manner, allow
the system to operate for at least 10 minutes before
taking the next temperature reading.
S-110 CHECKING EXPANSION VALVE
OPERATION
1. Remove the remote bulb of the expansion valve from the
suction line.
2. Start the system and cool the bulb in a container of ice
water, closing the valve. As you cool the bulb, the suction
pressure should fall and the suction temperature will rise.
3. Next warm the bulb in your hand. As you warm the bulb,
the suction pressure should rise and the suction tempera-
ture will fall.
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4. If a temperature or pressure change is noticed, the
expansion valve is operating. If no change is noticed, the
valve is restricted, the power element is faulty, or the
equalizer tube is plugged.
5. Capture the charge, replace the valve and drier, evacuate
and recharge.
S-111 FIXED ORIFICE RESTRICTOR DEVICES
The fixed orifice restrictor device (flowrator) used in conjunc-
tion with the indoor coil is a predetermined bore (I.D.).
It is designed to control the rate of liquid refrigerant flow into
an evaporator coil.
The amount of refrigerant that flows through the fixed orifice
restrictor device is regulated by the pressure difference
between the high and low sides of the system.
In the cooling cycle when the outdoor air temperature rises,
the high side condensing pressure rises. At the same time,
the cooling load on the indoor coil increases, causing the low
side pressure to rise, but at a slower rate.
Since the high side pressure rises faster when the tempera-
ture increases, more refrigerant flows to the evaporator,
increasing the cooling capacity of the system.
When the outdoor temperature falls, the reverse takes place.
The condensing pressure falls, and the cooling loads on the
indoor coil decreases, causing less refrigerant flow.
A strainer is placed on the entering side of the tube to prevent
any foreign material from becoming lodged inside the fixed
orifice restriction device.
If a restriction should become evident, proceed as follows:
1. Recover refrigerant charge.
2. Remove the orifice or tube strainer assembly and re-
place.
3. Replace liquid line drier, evacuate and recharge.
CHECKING EQUALIZATION TIME
During the "OFF" cycle, the high side pressure bleeds to the
low side through the fixed orifice restriction device. Check
equalization time as follows:
1. Attach a gauge manifold to the suction and liquid line dill
valves.
2. Start the system and allow the pressures to stabilize.
3. Stop the system and check the time it takes for the high
and low pressure gauge readings to equalize.
If it takes more than seven (7) minutes to equalize, the
restrictor device is inoperative. Replace, install a liquid line
drier, evacuate and recharge.