Technical data

7.3 Refrigerant Charge
Never introduce liquid refrigerant in the
low pressure side of circuit. Extreme care
must be taken to ensure that circuit is
correctly charged.
An insufficient charge will lead to poor machine
performance. In extreme cases, the low pressure
switch will cut in and lock the circuit.
Excessive charge will raise the condensation
pressure (which in extreme cases will cause the
high pressure switch to cut in and lock the circuit)
with a consequent increase in power consumption.
Under no circumstances must the
compressor be used as a vacuum pump
to purge circuit.
The refrigerant circuit must be charged whenever it
is emptied for maintenance purposes (leak repair,
compressor replacement, etc.). Charge quantities
are given in Section 9.
Before charging, the circuit must be vacuum-
purged and dried, reaching a minimum absolute
pressure of 50 Pa.
The refrigerant gas must be introduced to eliminate
vacuum and to charge the circuit to 90% of the total
required gas in liquid form through the appropriate
charging valve on liquid line at condenser outlet.
A refrigerant container should then be connected
to the charging valve on suction line, the container
should be held so that only gaseous phase
refrigerant is released (R22).
The compressor should be started and gas allowed
to flow from the refrigerant container until liquid in
the sight glass runs clear and gas temperature at
evaporator outlet has stabilised at around 5
o
C.
R407C units must be charged when the refrigerant
is in the liquid phase. A service valve is provided
for charging the unit at low pressure.
7.4 Compressor(s)
Compressors are supplied with the correct quantity
of lubricant required for operation. Under normal
operating conditions, lubricant will last the life of the
unit. Fluid top-up is not required as long as
refrigerating circuit operates correctly and no
repair operations have been carried out.
Compressor replacement (as a result of failure),
should be carried out by an Authorised York
Service Centre.
7.5 Filter Drier
Refrigerating circuits are provided with filter/driers.
The filter/driers are non-inspectable strainer type.
Filter/drier clogging will be indicated by bubbles in
the sight glass, or by a difference in temperature
upstream and downstream of filter/drier.
If bubbles persist after the changing cartridge, the
machine has lost part of its refrigerant charge
through one or more leaks which must be identified
and repaired.
7.6 Sight Glass
The sight glass is used to observe refrigerant flow
and moisture content. Bubbles in the flow indicate
that the filter/drier is clogged, or that refrigerant
charge is low.
A colour indicator is located inside the sight glass.
Compare the colour of the indicator with the scale
on the sight glass lock ring to determine the
moisture content of refrigerant. If moisture content
is too high, proceed as follows:
n
Discharge the circuit without releasing
refrigerant to the atmosphere. Vacuum-purge
the circuit and replenish the charge.
7-2 035B40022-000