Amana ANX, Service And Troubleshooting

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SERVICING
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NOTE: An optional method is to locate the
thermometer at the suction line service valve. Ensure
the thermometer makes adequate contact and is
insulated for best possible readings.
3. Refer to the superheat table provided for proper system
superheat. Add charge to lower superheat or recover
charge to raise superheat.
Superheat Formula = Suct. Line Temp. - Sat. Suct.
Temp.
EXAMPLE :
a. Suction Pressure = 143
b. Corresponding Temp. °F. = 50
c. Thermometer on Suction Line = 61°F.
To obtain the degrees temperature of superheat, subtract
50.0 from 61.0°F.
The difference is 11° Superheat. The 11° Superheat would
fall in the ± range of allowable superheat.
Subcooling on Expansion Valve System
1. Purge gauge lines. Connect service gauge manifold to
base-valve service ports. Run system at least 10 minutes
to allow pressure to stabilize.
2. Clamp a pipe clamp thermometer on the liquid line near
the liquid line service valve and 4-6” from the compressor
on the suction line.
a. nsure the thermometer makes adequate contact to
obtain the best possible readings.
b. The temperature read with the thermometer should be
lower than the saturated condensing temperature.
3. The difference between the measured saturated
condensing temperature and the liquid line temperature
is the liquid Subcooling value.
4. TXV-based systems should have a Subcooling value of
8°F +/- 1°F.
5. Add refrigerant to increase Subcooling and remove
refrigerant to decrease Subcooling.
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
temperature will fall.
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.
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
appearance of an undercharged unit. However, the unit
will have normal to high subcooling.
Locate the restriction, replace the restricted part, replace
drier, evacuate and recharge.
Overcharge Of Refrigerant
An overcharge of refrigerant is normally indicated by an
excessively high head pressure.
An evaporator coil, using an expansion valve metering
device, will basically modulate and control a flooded
evaporator and prevent liquid return to the compressor.
An evaporator coil, using a capillary tube metering device,
could allow refrigerant to return to the compressor under
extreme overcharge conditions. Also with a capillary tube
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
system containing non-condensables would be indicated.
If this system is observed:
1. Start the system.
2. Remove and capture 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.