Service manual

SERVICING
40
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 re-
striction 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.
S-113 OVERCHARGE OF REFRIGERANT
An overcharge of refrigerant is normally indicated by an
excessively high head pressure.
An evaporator coil, using an expansion valve metering de-
vice, will basically modulate and control a flooded evapora-
tor and prevent liquid return to the compressor.
An evaporator coil, using a fixed orifice metering device,
could allow refrigerant to return to the compressor under
extreme overcharge conditions. Also with a fixed orifice
metering device, extreme cases of insufficient indoor air
can cause icing of the indoor coil and liquid return to the
compressor, but the head pressure would be lower.
There are other causes for high head pressure which may
be found in the "Service Problem Analysis Guide."
If other causes check out normal, an overcharge or a sys-
tem containing non-condensables would be indicated.
If this is observed:
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
system contains non-condensables.
S-114 NON-CONDENSABLES
If non-condensables are suspected shut down the system
and allow the pressures to equalize, wait at least 15 min-
utes. Compare the pressure, to the temperature of the cold-
est 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.
Non-condensables are removed from the system by first
removing the refrigerant charge, replacing and/or installing
liquid line drier, evacuate and recharging.
S-115 COMPRESSOR BURNOUT
When a compressor burns out, high temperature develops
causing the refrigerant, oil and motor insulation to decom-
pose forming acids and sludge.
If a compressor is suspected of being burned-out, attach a
refrigerant hose to the liquid line dill valve and properly re-
move and dispose of the refrigerant.
Now determine if a burn out has actually occurred. Con-
firm 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 cleanup drier method.
CAUTION
DO NOT ALLOW THE SLUDGE OR OIL TO CONTACT
THE SKIN, SEVERE BURNS MAY RESULT.
NOTE: The Flushing Method using R-11 refrigerant is no
longer approved by Amana Refrigeration, Inc.
Suction Line Drier Clean-Up Method
Use AMANA part number R0157057 Suction Line Drier
Clean-Up Kit (41 cubic inches). This drier should be in-
stalled as close to the compressor as possible, either in a
vertical or horizontal position. It may be necessary to use
new tubing and form as required.
In all applications, the drier inlet must be above the drier
outlet to provide proper oil return to the compressor.
NOTE: At least twelve (12) inches of the suction line im-
mediately out of the compressor stub must be discarded
due to burned residue and contaminates.
1. Remove compressor discharge line strainer, liquid line
strainer and/or dryer and capillary tubes from indoor and
outdoor coils.
2. On an expansion valve coil, remove the liquid line drier
and expansion valve.
3. Purge all remaining components with dry nitrogen or
carbon dioxide until clean.