Maytag Amana PTC A Series Service Instructions Manual page 43

SERVICING
WARNING
NEVER TEST OPERATION WITHOUT THE UNIT IN
THE WALL SLEEVE. A SERIOUS CHANGE IN DESIGN
SPECIFICATIONS FOR AIR MOVEMENT THROUGH
THE EVAPORATOR AND CONDENSER COMPART-
MENTS, CAUSING THE FAN MOTOR TO OVER HEAT
AND THE REFRIGERATION SYSTEM TO BECOME
UNBALANCED WILL OCCUR WHEN THE UNIT IS
NOT INSTALLED IN THE WALL SLEEVE.
Efficient operation is dependent on a balanced system. One of
the most common reasons for inefficiency is the users failure
to adequately clean the condenser thereby creating reduced
air movement.
Cooling Performance Test Thermometers
The following precautions are necessary in observing the ther-
mometer readings in the cooling performance test.
1. Use two accurately calibrated refrigeration type thermom-
eters or a thermocouple potentiometer.
2. Thermometers are affected by body heat or changes in air
flow. Therefore, the thermometers must be secured in proper
locations with masking tape, wire or other applicable re-
tainers.
3. Readings should be observed without touching or moving
the thermometers.
Place Inlet Air
Thermostat Here
(Center in Grille)
Sling Psychrometer
The sling psychrometer is used to obtain the wet bulb tem-
perature in determining the percent relative humidity.
To obtain the wet bulb operate the sling psychrometer as
follows:
Saturate the wick (only once during procedure of obtaining
wet bulb readings) with clean water slightly below room
temperature. Psychrometer reading should be acquired five
to six feet in front of the unit and approximately four feet off
the floor.
NOTE: Direct discharge airflow away from the sling
psychrometer.
Place Discharge Air
Thermostat Here
The cooling performance test should not be employed when
outside temperatures are 20° below that of the room. Best
results are obtained when the test is conducted under peak
load conditions.
The air conditioner must operate at least 20 minutes on the
High Cool position before testing.
Cooling Test
The following temperature must be recorded for the cooling
performance test:
A. Dry bulb temperature of return air at conditioner. Locate
thermometer as illustrated.
B. Dry bulb temperature of air leaving conditioner. Thermom-
eter has to be located as illustrated.
C. The dry bulb thermometer temperature on the sling psy-
chrometer should be plus or minus 1°F within reading ob-
tained on thermometer in the return air. Check wet bulb
temperature on sling psychrometer and record same.
D. After the wet bulb temperature, dry bulb temperature, and
return air temperature have been recorded, proceed to cal-
culate the temperature difference as follows.
E. Subtract temperature obtained in Step B from temperature
obtained in Step A. The remainder temperature is used to
calculate from the Cooling Range Chart.
EXAMPLE: Assume a PTH15 unit is under test and the tem-
perature readings indicated below were obtained.
1. Return air D.B. temperature: 80°F, Step A.
2. Discharge air D.B. temperature: 69°F, Step B.
3. Return air, wet and dry bulb temperature as recorded in
Step C: Dry Bulb 80°F, Wet Bulb 75°F.
4. In left hand column of Cooling Capacity Charge headed
Dry Bulb, find the 80° value.
5. In column headed Wet Bulb find the 75°F value and find
the value 8 -13 in the cooling range column under the Model
"PTH153 PTH154".
This data shows that the temperature of the air passing through
the cooling coil is reduced at least 8°F but not more than 13°F.
This example unit is operating normally for the existing condi-
tions.
For the example unit under test, the temperature difference
was 11°F (80°F, return air, minimum 69°F discharge air). Since
the value is within the listed cooling range 8 - 13, this unit is
considered to be operating normally.
For Total Power Input Test (wattage) the following addi-
tional readings must be recorded after the unit under
test is interconnected with a wattmeter.
• Outdoor dry bulb temperature. Avoid direct exposure of
thermometer to sunlight or to hot condenser discharge air.
• Total watts input, measured by wattmeter or calculate by
multiplying applied voltage by unit amps.
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