| Complaint |
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| Possible Causes |
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a. | High suction pressure and low head pressure | a. | Compressor may be bad |
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b. | High suction pressure and low head pressure | b. | Expansion valve opened, too | ||||||
| Low superheat and low subcooling |
| much oil |
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c. | High suction pressure and high head pressure | c. | Overcharge |
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| Low superheat and high subcooling | d. |
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d. | High to normal suction pressure and high head pressure |
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| Low subcooling | e. | Air | restricted, | dirty | condenser, | |||
e. | High suction pressure and high head pressure | ||||||||
| Low subcooling |
| bad condenser fans |
|
| ||||
f. | High suction pressure and high head pressure | f. | High | room | temperature, | high | |||
| High superheat |
| evaporator load |
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|
| |||
g. | Low suction pressure and low head pressure | g. | Undercharge |
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| High superheat and low subcooling | h. | Liquid | line |
| restricted | after | ||
h. | Low suction pressure and low to normal head pressure |
| |||||||
| High superheat and high subcooling |
| receiver, | solenoid | valve | ||||
|
|
| restricted |
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| ||
i. | Low suction pressure and low head pressure | i. | Suction line restricted |
| |||||
| Low subcooling | j. | Air | restricted | at | evaporator, | |||
j. | Low suction pressure and low head pressure | ||||||||
| Low superheat and low subcooling |
| evaporator iced |
|
|
| |||
k. | Low suction pressure and low to normal head pressure | k. | Evaporator restricted |
|
| ||||
| High superheat and normal to high subcooling | l. | Expansion valve restricted |
| |||||
l. | Low suction pressure and normal head pressure |
| |||||||
| High superheat and normal subcooling | m. Both evaporator and condenser | |||||||
m. Low suction pressure and high head pressure | |||||||||
| High superheat and high subcooling |
| restricted |
|
|
|
| ||
n. | Low suction pressure and high head pressure | n. | Liquid | line | restricted before | ||||
| High superheat and high subcooling |
| receiver |
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|
| ||
o. low to normal suction pressure and high head pressure | o. | Condenser restricted |
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| |||||
| High to normal superheat and high subcooling |
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6. Valve Operation
SPINDLE BACK POSITION SPINDLE FRONT POSITION SPINDLE MIDDLE POSITION
Fig. 2.1 Valve Operation
Back Position: Process and manometer port closed for normal operation
Front Position: Main connection to liquid or suction line closed
Middle Position: All ports open for vacuum, charge and measurement
- 8 -
