Receiver Drier

TM 10-3930-673-34

d. Receiver Drier. The high pressure liquid

refrigerant moves from the condenser coil to the

receiver drier, where the refrigerant is stored and

filtered. Moisture is the major enemy of the air

conditioning system, and desiccant inside the

receiver drier will absorb only a small amount. The

container of desiccant inside the receiver drier may

break open and contaminate the system if any

attempt is made to dry the desiccant, or if more

moisture is inside the system than the desiccant can

absorb. Every effort should be made to remove all

moisture from the system and install a new receiver

drier if its condition is questionable. Installation of

a new receiver drier is recommended is necessary

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each time any part of the refrigeration system is

open to the atmosphere.

e. Expansion Valve. The expansion valve is

installed in the air conditioning system to lower

pressure before the refrigerant enters the

evaporator coil. This reduction in pressure is done

by passing the refrigerant through a small orifice.

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f. Evaporator Coil. The evaporator coil is the low

pressure component where liquid refrigerant

absorbs heat from surrounding air. The expansion

valve bleeds high pressure refrigerant into the low

pressure evaporator coil. The refrigerant expands

rapidly in the evaporator coil and its temperature is

quickly reduced. The refrigerant absorbs heat from

the air when the blower fan circulates air over the

evaporator coil fins. The exchange of heat from the

air to the refrigerant depends upon the difference in

temperature. During high heat load, such as usually

encountered when the system is first turned on, the

temperature difference is great and the refrigerant

will absorb heat quickly. The fan blower can be set

at its highest setting to circulate large quantities of

warm air around the evaporator coil. After the cab

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has been cooled, the fan speed should be reduced so

that already cool air will have longer time to yield to

the refrigerant as it passes the evaporator coil.

15-3