Purpose
The expansion valve atomizes liquid refrigerant to facilitate cooling of the evaporator.
Function
The expansion valve reduces the pressure of liquid refrigerant rapidly to facilitate vaporization of the atomized refrigerant at the evaporator, and adjusts the refrigerant amount sent into the evaporator.
Construction
The expansion valve consists of the following parts:
Diaphragm
Temperature sensor
Shaft
Expansion valve body
Ball valve
Spring

Operation
Adjustment of the refrigerant amount supplied to the evaporator is performed by the ball valve opening angle in the expansion valve.
The opening angle adjustment is performed according to the balance of the following forces:

Refrigerant pressure (Pd) in diaphragm
Refrigerant gas pressure (PI) of evaporator under diaphragm
Spring force (Fs) pushing up ball valve
If the refrigerant gas temperature from the evaporator increases, the expansion valve increases the amount of refrigerant according to the following operations:

The temperature of the temperature sensor tightly sealed against the diaphragm increases.
The refrigerant in the diaphragm warms and the Pd increases.
If this Pd increases more than PI + Fs, the diaphragm is pressed down.
The shaft installed to the temperature sensor end presses down the ball valve.
The amount of refrigerant is increased.
If the refrigerant gas temperature from the evaporator decreases, the expansion valve decreases the amount of refrigerant flow according to the following operation:

The temperature of the temperature sensor tightly sealed against the diaphragm decreases.
The refrigerant temperature in the diaphragm decreases and the Pd decreases.
The Pd decreases less than PI + Fs.
The ball valve installed to the temperature sensor end is pressed up.
The amount of refrigerant is decreased.
Fail-safe
Function not equipped.
Evaporator Inspection
Expansion Valve Removal/InstallationRear End Panel Installation [Panel Replacement]
Symbol Mark
Installation Procedure
1. When installing new parts, measure and adjust the body as necessary to conform
with standard dimensions.
2. Drill holes for the plug welding before installing the new parts.
3. After temporarily installing new parts, make sure the related parts fit p ...
Fuel Filler Cap
Purpose, Function
Releases evaporative gas from the fuel tank if there is a malfunction in
the evaporative gas passage between the fuel tank and the intake manifold. As
a result, deformation of the fuel tank caused by evaporative gas pressure is
prevented.
Construction
T ...
Main Relay Control [Skyactiv G 2.0]
Outline
Supplies power to each part by switching the main relay on/off at the optimal
timing according to the vehicle conditions.
Block Diagram
Operation
When the ignition is switched ON, the main relay turns on and electrical
power is supplied to each sensor and devic ...