Sharp AF-S100RX Service Manual Download Page 36

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Section

Sealed System

-10

High-pressure cutout

A high-pressure cut-out switch with a rating higher than
510 psi will keep the recovery unit from prematurely
relieving high pressure when recovering R-410A. Some
manufacturers offer equipment with an override switch
so a higher-pressure switch is used when recovering
R-410A. The problem with having a dual switch (550 psi
or higher) is that an R-410A recovery refrigerant tank
(DOT 400) and a standard recovery tank (DOT 350) are
virtually indistinguishable unless marked. Using recovery
equipment with a high-pressure switch rated at 550 psi
with a standard DOT 350 recovery tank can cause the
relief valve to blow, creating an extremely dangerous
situation.

Maintaining Equipment

Proper maintenance of equipment is critical for safety.
Calibrate the gauges on the manifold set before every
use and annually check the manifold set for leakage.
Inspect the hoses for nicks or cracks and that the gaskets
are in good shape. Make sure the valve assemblies are
not leaking. Inspect the recovery unit periodically to
ensure that it is safe to use. If degradation in the rate of
recovery is noticed, check the built-in or external lter.

Definitions

Recovery:

To remove refrigerant in any condition from a system
and store it in an external container without necessarily
testing or processing it in any way.

Recycling:

To clean refrigerant for reuse by oil separation and
single or multiple passes through devices, such as
replaceable core filter-driers, which reduce moisture,
acidity and particulate matter. This term usually applies
to procedures implemented at the field job site or at a
local service shop.

Reclaim:

To reprocess refrigerant to new product specifications
by means which may include distillation, will require
chemical analysis of the refrigerant to determine that
appropriate product specifications are met. This term
usually implies the use of processes or procedures
available only at a reprocessing or manufacturing facility.

Basic Components

The basic components of an air conditioner are a
compressor, condenser, evaporator and heat exchanger
(capillary tube and suction line). Filter driers are
installed when the sealed system is entered and/or the
sealed system components are serviced.

Refrigerant Cycle

The refrigerant cycle is a continuous cycle that occurs
whenever the compressor is in operation. Liquid
refrigerant is evaporated in the evaporator by the heat
of the room being cooled. The refrigerant vapor is then
drawn from the evaporator, through the suction line, to
the compressor.
Compression raises the pressure and temperature of the
vapor in the compressor and the vapor is then forced
through the discharge valve into the discharge line and
into the condenser. Air passing over the condenser
surface removes heat from the high pressure vapor
which then condenses to a liquid. The liquid refrigerant
then flows from the condenser to the evaporator through
the small diameter liquid line (capillary tube).
Before it enters the evaporator, the liquid refrigerant is
sub-cooled in the heat exchanger by the low
temperature suction vapor in the suction line. When
refrigerant is added, the frost pattern will improve, the
suction and discharge pressures will rise, the condenser
will become hot and the wattage will increase.