Valeooscope - Air Conditioning System Thermal comfort loop

11. The components of the A/C Loop

11.8.1.1 The orifice tube

11.8.1.2 The accumulator

Operation: The orifice tube is a tube with a given length and cross-section which expands the refrigerant but, un- like the expansion valve, is unable to regulate flow rate and superheating. The orifice tube is always associated with an accu- mulator at the evaporator outlet. Orifice tubes are made up of three main parts: g A metal tube with a chamfered inlet g A plastic tube body g An inlet and outlet filter

The accumulator has a similar function to the receiver drier but works on the gaseous side of the A/C loop. The accumulator protects the components of the system; it is located on the low pressure side of the circuit between the evaporator outlet and the compressor suction port.

Compressor

Evaporator

Condenser

Accumulator

To evaporator

O-Ring

Fine mesh filter inlet

Orifice tube

Roles: 1. To provide compressor protection, preventing compressor failure due to liquid slugging 2. To retain moisture and contaminants from the system (during the accumulators life time) 3. To ensure oil return and assure that only refrige- rant is returning to the compressor.

From condenser

Fixed small diameter bronze tube (rextriction)

From condenser

A/C system

Replacement:

Gaseous refrigerant

Gaseous refrigerant

If the A/C loop is contaminated, then the orifice tube becomes clogged. In this case, replace the orifice tube. The orifice tube must always be replaced when another important part of the circuit is replaced (compressor, condenser, evapora- tor, receiver drier). Warning ! Flush the A/C loop before installing a new orifice tube.

Oil

Liquid refrigerant

Oil

Contaminants

Advice on replacing accumulators:

The accumulator is a drier filter that must be replaced every 3 years or whenever the circuit is opened.

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