Service manual

SERVICING
38
4. Convert the suction pressure gauge reading to tempera-
ture by finding the gauge reading in Temperature - Pres-
sure Chart and reading to the left, find the temperature
in the °F. Column.
5. The difference between the thermometer reading and
pressure to temperature conversion is the amount of
superheat.
EXAMPLE:
a. Suction Pressure = 84
b. Corresponding Temp. °F. = 50
c. Thermometer on Suction Line = 63°F.
To obtain the degrees temperature of superheat subtract
50.0 from 63.0°F.
The difference is 13° Superheat. The 13° Superheat would
fall in the ± range of allowable superheat.
SUPERHEAT ADJUSTMENT
The expansion valves used on Amana coils are factory set
and are not field adjustable. If the superheat setting be-
comes disturbed, replace the valve.
S-109 CHECKING SUBCOOLING
Refrigerant liquid is considered subcooled whenever its tem-
perature is lower than the saturation temperature corre-
sponding to its pressure. The degree of subcooling equals
the degrees of temperature decrease below the saturation
temperature at the existing pressure.
1. Attach an accurate thermometer or preferably a ther-
mocouple type temperature tester to the liquid line as it
leaves the condensing unit.
2. Install a high side pressure gauge on the high side ser-
vice valve at the front of the unit.
3. Record the gauge pressure and the temperature of the
line.
4. Convert the discharge pressure gauge reading to tem-
perature by finding the gauge reading in Temperature -
Pressure Chart and reading to the left, find the tem-
perature in the °F. Column.
5. The difference between the thermometer reading and
pressure to temperature conversion is the amount of
subcooling.
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50 60 70 80 90 100 110 120
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SUPERHEAT @ O.D. UNIT
OUTDOOR TEMPERATURE
DESIRED SUPERHEAT vs OUTDOOR TEMPERATURE
90° F Indoor
70° F Indoor
75° F Indoor
80° F Indoor
85° F Indoor