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/InstallationTurning the Engine Off
WARNING
Do not stop the engine while the vehicle is moving:
Stopping the engine while the vehicle is moving for any reason other than in
an emergency is dangerous.
Stopping the engine while the vehicle is moving will result in reduced braking
ability due to the loss of power braking, which co ...
Control System Personalization Features Setting Procedure
1. Connect the M-MDS to DLC-2.
2. After the vehicle is identified, select the following items from the initial
screen of the M-MDS.
Select the “Module Programming”.
Select “Programmable Parameters”.
Select menu in the R_BCM.
3. Select an item name, and then ...
Propeller Shaft Inspection
1. Measure the propeller shaft center runout using the dial gauge.
If it exceeds the maximum specification, replace the propeller shaft as a
single component.
Propeller shaft maximum runout
0.8 mm {0.031 in}
2. Inspect the play and rotation of the joint by turning ...