Chevrolet 1980 Light Duty Truck Service Manual page 50

1B-4 AIR C O N DITIO NING
The valve consists primarily of the power element,
body, actuating pins, seat and orifice. At the high pressure
liquid inlet, is a fine mesh screen which prevents dirt, filings
or other foreign matter from entering the valve orifice.
When the valve is connected in the system, high
pressure liquid refrigerant enters the valve through the
screen from the receiver-dehydrator or condenser and
passes on to the seat and orifice. Upon passing through the
orifice the high pressure liquid becomes low pressure liquid.
The low pressure liquid leaves the valve and flows into the
evaporator core where it absorbs heat from the evaporator
core and changes to a low pressure vapor, and leaves the
evaporator core as such. The power element bulb is clamped
to the low pressure vapor line just beyond the outlet of the
evaporator (fig. IB-2).
Accum ulator-C-K, G Series (Fig. 1 B-3)
The accumulator is located at the evaporator outlet. Its
most important function is not to "accumulate" although
this too is important. Its primary function is to separate
liquid retained from vapor, retain the liquid and release the
vapor to the compressor.
Thus, in and ideal accumulator with no oil bleed hole,
and in a correctly designed system, no liquid can get to the
compressor.
In an actual accumulator, there is some entrained
liquid in the vapor stream to the compressor.
Flow out of the accumulator to the compressor consists
mostly of vapor with the addition of entrained liquid and
liquid flow through the oil bleed hole.
A bag of desiccant (dehydrating agent) is located in the
accumulator as a moisture collecting device.
There is no sight glass in the accumulator-clutch cycle
system.
Expansion Tube--C-K, G Series
Expansion tube flow rate depends on pressure
difference and on subcooling; however, the flow rate is more
sensitive to subcooling.
The expansion tube is located in the evaporator inlet
line (fig. IB-4).
Fig. 1 B -4-E xpansion Tube
LIG H T T R U C K S ER V IC E M AN UAL