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SERVICING
41
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.
4. If a temperature or pressure change is noticed, the expan-
sion 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-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.
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.
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.
V
IOLATION OF EPA REGULATIONS MAY RESULT
IN FINES OR OTHER PENALITIES.
NOTICE
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 clean-up is
not necessary.
If acid level is unacceptable, the system must be cleaned by
using the clean-up drier method.
CAUTION
DO NOT ALLOW THE SLUDGE OR OIL TO CONTACT
THE SKIN, SEVERE BURNS MAY RESULT.