TM 5-3805-281-24-1
Theory of Operation
RECEIVER/DRYER OPERATION
The receiver/dryer is a reservoir to store excess liquid
refrigerant in the system. Excess refrigerant is required for
two reasons:
Outside air temperature and humidity have an effect on
the minimum quantity of refrigerant required in the system
for the air conditioner to operate at maximum efficiency.
The higher the temperature and humidity, the more
refrigerant required in the system. More refrigerant is
required due to the expansion valve opening farther
allowing more refrigerant into the low pressure side of the
system.
Refrigerant hoses allow a small amount of refrigerant to
migrate through their walls. Extra refrigerant stored in the
system allows for a longer period of time before additional
refrigerant is needed.
The receiver/dryer also contains two filters (E) and
desiccant (F) between the filters. The filters remove solid
materials which could be generated by a compressor
failure, debris left in the system due to improper service
procedures, or particles caused by corrosion of metal
parts due to moisture and acids in the system (also
caused by improper service procedures).
Desiccant is used to absorb moisture. If too much
moisture gets into the system, the desiccant may not be
able to absorb it all. When moisture is combined with
refrigerant oil, a sludge is formed. This sludge does not
permit moving parts to be adequately lubricated. When
9031
05
moisture is combined with refrigerant, hydrofluoric and
6
hydrochloric acids are formed. These acids are very
corrosive to metal surfaces and leakage will eventually
develop. If the air conditioning system is left open for a
period of time or if the plugs are removed from the
receiver/dryer, the desiccant will also absorb moisture
from the air. The receiver/dryer contains a color moisture
indicator. (Blue) indicates dryer is dry. (Pink) indicates
A--Inlet Port
moisture in the desiccant. Evacuating the system will not
B--Sight Glass
C--Outlet Port
remove moisture from the desiccant. You must replace
D--Pickup Tube
the receiver/dryer.
E--Filter
F--Desiccant
G--Strainer
H--Spring
I--Receiver/Dryer
J--Wet/Dry Indicator
Continued on next page
TX,9031,UU3144 1913AUG961/2
