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/InstallationHood Latch Switch Inspection
1. Disconnect the negative battery cable..
2. Remove the front bumper..
3. Disconnect the hood latch switch connector..
4. Verify that the continuity is as indicated in the table.
NOTE:
Inspect the continuity when the hood is open and closed.
If the operation as i ...
Refrigerant System Service Warnings
Handling Refrigerant
Avoid breathing air conditioning refrigerant or lubricant vapor. Exposure
may irritate eyes, nose and throat. Also, due to environmental concerns, we
urge use of recovery/recycling/recharging equipment when draining HFC-134a from
the air conditioning system. If a ...
Active Command Modes Inspection [Blind Spot Monitoring (Bsm)]
1. Connect the M-MDS to the DLC-2.
2. After the vehicle is identified, select the following items from the initialization
screen of the M-MDS.
a. Select “DataLogger”.
b. Select “Modules”.
c. Select “BSML” or “BSMR”.
3. Select the simulation items from the PID table.
4. ...