WD Catalog 2018

4-11

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Note:

Intercoolers, are also called aftercoolers or chassis-

mounted charge-air coolers. These devices may be

installed on the engine or in front of the radiator on

some heavy duty vehicles. They are designed to

achieve improved fuel economy and performance, and

lower emissions by reducing air temperature at the

intake manifold. The cooler, denser air boosts horse-

power, efficiency and engine durability. For these

reasons, intercooler installation is on the increase on

heavy duty trucks.

In some intercooler applications, the condenser used for AC may be mounted in

front of the radiator and below the intercooler. Figure 11-9 in

Chapter 11

shows

this condenser location.

Receiver–Drier

The receiver-drier functions as a drier, refrigerant filter and temporary storage

tank for refrigerant moving through the AC system. When refrigerant leaves

the condenser as a liquid, it flows to the receiver-drier. Figure 4-8 shows a

cutaway view of a receiver-drier. Refrigerant enters at the top and flows

through a desiccant material and filter before it moves on through a pickup

tube near the tank bottom. The most common desiccant is a molecular sieve.

This is a porous material, usually in the form of 1/8 inch balls, that attract and

hold moisture.

The desiccant commonly used with R-12 is identified as XH-5. It is not

compatible with R-134a. Many driers in both new and replacement systems are

now using an XH-9 desiccant which is compatible with both R-12 and R-134a.

Driers that do not carry a special labeling are probably only good for R-12

usage.

RECEIVER-DRIER

SIGHT GLASS MAY INCLUDE

MOISTURE INDICATOR

INLET FROM CONDENSER

OUTLET TO EXPANSION VALVE

FILTER PADS

AND SCREENS

PICKUP TUBE

MOISTURE AND CONTAMINANTS

TRAPPED BY FILTERS, SCREENS,

AND DESICCANT

SPRING

Note:

Moisture (water) or particles can cause system mal-

functions and corrosion. They can block the natural

flow of refrigerant at the expansion valve. Moisture

can change state there and form ice. It may also mix

with the other elements inside the system ( refriger-

ant and the oil) to form acid.

Accumulator

Figure 4-8

This illustration shows the

inside of a typical receiver-

drier. Note the path of the

arrows which indicate the

movement of refrigerant.

The desiccant, filter(s), and

screens trap any water or

particles that might acci-

dentally be inside the sys-

tem.