S-108 Superheat - Amana PHB**C Service Instructions Manual

SERVICING

S-108 SUPERHEAT

The expansion valves are factory adjusted to maintain 12 to
18 degrees superheat of the suction gas. Before checking
the superheat or replacing the valve, perform all the proce-
dures outlined under Air Flow, Refrigerant Charge, Expan-
sion Valve - Overfeeding, Underfeeding. These are the most
common causes for evaporator malfunction.
CHECKING SUPERHEAT
Refrigerant gas is considered superheated whenever its tem-
perature is higher than the saturation temperature correspond-
ing to its pressure. The degree of superheat equals the de-
grees of temperature increase above the saturation tempera-
ture at existing pressure. See Temperature - Pressure Chart.
1. Attach an accurate thermometer or preferably a thermo-
couple type temperature tester to the suction line at a
point at least 6" from the compressor.
2. Install a low side pressure gauge on the suction line ser-
vice valve at the outdoor unit.
3. Record the gauge pressure and the temperature of the
line.
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.
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
50
DESIRED SUPERHEAT vs OUTDOOR TEMPERATURE
60 70
OUTDOOR TEMPERATURE
5. The difference between the thermometer reading and pres-
sure to temperature conversion is the amount of super-
heat.
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
tory set and are not field adjustable. If the superheat setting
becomes disturbed, replace the valve.
80 90
®
brand coils are fac-
100 110 120
53