Car A/C Accumulator

By 8 August 2014

An accumulator is used when an FOV metering device is used. The accumulator is fitted between
the evaporator and the compressor.

The function of the accumulator is as follows:

1. To ensure that the refrigerant leaves the accumulator as a vapour and not a liquid state for
the compressor to induce.
2. To ensure it is free from dirt to stop any excessive wear or premature failure of components.
3. To remove moisture ensuring no ice can form on any components within the system which
may cause a blockage and to ensure no internal corrosion can form.
4. To act as a temporary reservoir to supply the system under varying load conditions.
5. To add lubricating oil for system components like the compressor.
6. Often to house the low pressure switch/sensor.

The refrigerant enters the accumulator from the evaporator in liquid/vapour form. It enters
through the inlet (3) creating a vortex and flowing around the cap (4). The refrigerant
passes through the desiccant where it is cleaned and moisture is removed.The vapour collects
under the cap (4) where it is extracted through the outlet. During extraction it passes through
a U tube in which it is mixed with oil from the small bleed hole (6).This bleed hole allows very
small quantities of liquid refrigerant mixed with lubricating oil (3%) to flow with the refrigerant
vapour to the compressor. Because the liquid refrigerant vapour is in such small quantities
there is no danger of compressor damage.

The receiver-drier or accumulator must be replaced under any of the following circumstances:

? If the A/C system is opened to moisture for more than 3 hours then the receiver/accumulator
must be replaced.
? Under service conditions – every two years.
? Compressor seizure or any possibility of foreign matter in the system.
? Excessive moisture in system causing icing.