Dehydrating Sealed Refrigeration System; Leak Testing; Testing Systems Containing A Refrigerant Charge; Testing Systems Containing No Refrigerant Charge - Fisher & Paykel RX256DT4X1 FP Service Manual

NOTE: Ensure test cord cables and fuses meet specifications for unit under test (see Technical
Sheet for unit under test).
6. Replace compressor protector cover securely.
7. Plug test cord into outlet, then press and release start cord switch.
To avoid risk of damage to compressor windings, immediately disconnect (unplug) test cord from
power source if compressor does not start. Damage to compressor windings occurs if windings
If compressor runs when direct wired, it is working properly. Malfunction is elsewhere in system.
If compressor does not start when direct wired, recover system at high side. After the system is
recovered, repeat compressor direct wire test.
If compressor runs after system is recovered (but would not operate when wired direct before
recovery) a restriction in sealed system is indicated.
If motor does not run when wired direct after recovery, replace faulty compressor.
13.7

Dehydrating Sealed Refrigeration System

Moisture in a refrigerator sealed system exposed to heat generated by the compressor and motor
reacts chemically with refrigerant and oil in the system and forms corrosive hydrochloric and
hydrofluoric acids. These acids contribute to breakdown of motor winding insulation and corrosion of
compressor working parts, causing compressor failure.
In addition, sludge, a residue of the chemical reaction, coats all surfaces of sealed system, and will
eventually restrict refrigerant flow through capillary tube.
To dehydrate sealed system, evacuate system (see paragraph Evacuation).
13.8

Leak Testing

To avoid risk of serious injury or death from violent explosions, NEVER use oxygen or acetylene
for pressure testing or cleaning out of refrigeration systems. Free oxygen will explode on contact
with oil. Acetylene will explode spontaneously when put under pressure.
It is important to check sealed system for refrigerant leaks. Undetected leaks can lead to repeated
service calls and eventually result in system contamination, restrictions, and premature compressor
failure.
Refrigerant leaks are best detected with halide or electronic leak detectors.
13.8.1

Testing Systems Containing a Refrigerant Charge

1. Stop unit operation (turn refrigerator off).
2. Holding leak detector exploring tube as close to system tubing as possible, check all piping, joints,
and fittings.
NOTE: Use leak detection fluid on areas leak detector cannot reach or reliably test.
13.8.2

Testing Systems Containing No Refrigerant Charge

1. Connect cylinder of nitrogen, through gauge manifold, to process tube of compressor and liquid line
strainer.
remain energised when compressor is not running.
CAUTION
DANGER
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