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/InstallationNeutral Switch Removal/Installation [C66 M R]
1. Disconnect the negative battery cable..
2. Remove the air cleaner component. (ex: air cleaner, air hose).
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
1
Neutral switch connector
2
Neutral ...
Crankshaft Position (CKP) Sensor Removal/Installation
CAUTION:
When foreign material such as an iron chip is on the CKP sensor, it can cause
abnormal output from the sensor because of flux turbulence and adversely affect
the engine control. Be sure there is no foreign material on the CKP sensor when
replacing.
Do not assemble t ...
Passenger Compartment Temperature Sensor Inspection [Full Auto Air Conditioner]
1. Measure the temperature around the passenger compartment temperature sensor
and measure the resistance between passenger compartment temperature sensor terminals
A and B.
If the characteristics of the passenger compartment temperature sensor are
not as shown in the graph, replace t ...