S-111 Fixed Orifice Restriction Devices; S-112 Checking Restricted Liquid Line; S-113 Refrigerant Overcharge; S-114 Non-Condensables - Goodman GPH13 Service Instructions Manual

SERVICING
S-111 FIXED ORIFICE RESTRICTION
DEVICES
The fixed orifice restriction 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
restriction device is regulated by the pressure difference be-
tween 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, increas-
ing 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.
If a restriction should become evident, proceed as follows:
1. Recover refrigerant charge.
2. Remove the orifice assembly and clean or replace.
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 restric-
tion device is inoperative. Replace, install a liquid line drier,
evacuate and recharge.

S-112 CHECKING RESTRICTED LIQUID LINE

When the system is operating, the liquid line is warm to the
touch. If the liquid line is restricted, a definite temperature
drop will be noticed at the point of restriction. In severe cases,
frost will form at the restriction and extend down the line in the
direction of the flow.
Discharge and suction pressures will be low, giving the ap-
pearance of an undercharged unit. However, the unit will have
normal to high subcooling.
If a restriction is located, replace the restricted part, replace
drier, evacuate and recharge.
38

S-113 REFRIGERANT OVERCHARGE

An overcharge of refrigerant is normally indicated by exces-
sively high head pressure and/or liquid return to the compres-
sor.
Evaporator coils with a fixed orifice metering device could
allow refrigerant to return to the compressor under extreme
overcharge conditions.
If high head pressure is not indicated, an overcharge or a sys-
tem containing non-condensables could be the problem.
If overcharging is indicated:
1. Start the system.
2. Remove small quantities of gas from the suction line dill
valve until the head pressure is reduced to normal.
3. Observe the system while running a cooling performance
test, if a shortage of refrigerant is indicated, then the sys-
tem contains non-condensables. See S-114 Non-
Condensables.

S-114 NON-CONDENSABLES

Check for non-condensables.
1. Shut down the system and allow the pressures to equalize
for a minimum of 15 minutes.
2. Take a pressure reading.
3. Compare this pressure to the temperature of the coldest
coil since this is where most of the refrigerant will be. If the
pressure indicates a higher temperature than that of the
coil temperature, non-condensables are present.
To remove the non-condensables.
1. Remove the refrigerant charge.
2. Replace and/or install liquid line drier
3. Evacuate and recharge.

S-115 COMPRESSOR BURNOUT

When a compressor burns out, high temperature develops caus-
ing the refrigerant, oil and motor insulation to decompose form-
ing acids and sludge.
If a compressor is suspected of being burned-out, attach a
refrigerant hose to the liquid line dill valve and properly remove
and dispose of the refrigerant.
Now determine if a burn out has actually occurred. Confirm by
analyzing an oil sample using a Sporlan Acid Test Kit, AK-3 or
its equivalent.
Remove the compressor and obtain an oil sample from the
suction stub. If the oil is not acidic, either a burnout has not
occurred or the burnout is so mild that a complete cleanup is
not necessary.
If acid level is unacceptable the system must be cleaned by
using the drier cleanup method.