Sealed System Diagnosis; Symptoms Of An Overcharge; Symptoms Of Refrigeration Shortage - Fisher & Paykel RX256DT4X1 FP Service Manual

12

SEALED SYSTEM DIAGNOSIS

CONDITION Suction
pressure
variation
from
normal
Increase
Refrigerant
Overcharge
Decrease Decrease or
Shortage of
Refrigerant
Decrease Decrease or
Partial
Restriction
Near
Air in
Normal
System
Decrease
Low Ambient
Installations
(High
Ambients the
Increase
Additional
Heat Load
Increase
Inefficient
Compressor
12.1

Symptoms of an Overcharge

• Above normal freezer temperatures.
• Longer than normal or continuous run.
• Freezing in fresh food compartment, especially on forced air meat keeper models.
• Higher than normal suction and head pressure.
• Higher than normal wattage.
• Evaporator inlet and outlet temperatures warmer than normal.
• Suction tube temperature below ambient.
suction temperature is colder than ambient.
Various conditions could indicate an overcharge. For example, if the cooling coil is not defrosted at
regular intervals, due to a failure of the defrost system, the refrigerant will "flood out" and cause the
suction line to frost or sweat. The cause of this problem should be corrected rather than to purge
refrigerant from the system.
considered normal package temperatures) or continuous running of the compressor for a variety of
reasons, or the freezer fan motor not running, may give the indication of an overcharge.
12.2

Symptoms of Refrigeration Shortage

• Rise in food product temperature in both compartments. (See Note 1 below.)
• Long or continuous run time.
• Look for obvious traces of oil that would occur due to a leak or cracked refrigerant line.
• Lower than normal wattage.
• Compressor will be hot to touch because of the heat generated by the motor windings from long
continuous running. It will not be as hot as it would be with a full charge and long run times for
some other reason such as a dirty condenser.
Head T1 inlet
pressure temperature
variation variation from
from normal
normal
Increase Warmer
Colder
Increase
See Text
Colder
Increase
See Text
Note 2
Increase Warmer
Decrease Colder
Increase Warmer
Normal or Warmer or
Decrease Colder
Always check for separated heat exchanger when
Running the freezer section colder than necessary (-2 to -1
87
T2 outlet T3 suction
temperature temperature
variation from variation from
normal
Warmer
Warmer
Warmer
Warmer
Warmer
Warmer
Warmer
321023
Wattage
variation
from
normal normal
Colder Increase
Warmer Decrease
Warmer Decrease
Warmer Increase
Warmer Decrease
Warmer Increase
Warmer Decrease
O
F is