Specifications

Section 3
3-16
TOYOTA Technical Training
The outlet of the receiver-drier connects to a siphon tube that goes to the
bottom of the container. This acts as a liquid/vapor separator and ensures
o
nly liquid refrigerant is supplied to the expansion valve. In
a
ddition,
the end of the siphon tube has a very fine mesh screen to filter debris from
the refrigerant and oil. This protects the expansion valve and the
compressor from mechanical damage.
To protect the expansion valve from being blocked by ice, any moisture
in the refrigerant is removed as it passes through a desiccant in the
receiver-drier. A desiccant is a chemical that bonds water (H
2
O) with other
molecules to form a different molecule. There is a limit to the
amount of
moisture the desiccant can hold. After the desiccant becomes saturated,
any additional moisture will pass through the system. A receiver-drier left
open (fittings removed) on the shelf or in the vehicle for
about 10 minutes
(80% humidity) will become fully saturated and unusable.
The receiver-drier desiccant material is different in HFC134a and older
CFC-12 systems. Do not interchange them. Moisture inside the system
is absorbed by the desiccant and is not fully removed during system
evacuation or the vacuum process prior to recharging. Moisture remaining
inside the system or receiver-drier can result in internal icing of the
expansion valve and cause erratic system operation.
The receiver-drier is a service part and should be replaced any time
the system has leaked, or been left open (even for a short time), or when a
component such as a compressor
or reed valve has failed.
In some systems, the receiver-drier contains a sight glass that allows you
to visually confirm that only liquid refrigerant is passing on to the
expansion valve. This may be useful during preliminary diagnosis, but it
is not accurate in determining if the system has the proper amount of
refrigerant. Some models use a “modulator-drier” that is part of the
condenser. On some Toyota models, the functions of a receiver-drier are
built into the sub-cool condenser; desiccant is stored in the modulator
portion of the sub-cool. On other models, the receiver-drier is separate
from the sub-cool condenser.
Note:
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