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.
Intermediate Shaft Removal/Installation
WARNING:
The steering column (EPS motor) temperature increases directly after continuous
turning of the steering mechanism which could cause burns if it is touched.
Before performing any servicing, verify that the steering column has cooled
off.
1. Rotate the steering wheel un ...
Magnetic Clutch Adjustment [Full Auto Air Conditioner]
1. Measure the clearance around the entire circumference between the pressure
plate and A/C compressor pulley using a thickness gauge.
2. Verify the clearance.
If not within the specification, remove the pressure plate and adjust the
clearance by changing the shim (0.2 mm {0.008 i ...
Seat Warmer Control Unit Inspection
WARNING:
Handling a front seat (with built-in side air bag) improperly can accidentally
operate (deploy) the air bag, which may seriously injure you. Read the service
warnings/cautions before handling a front seat (with built-in side air bag)..
CAUTION:
After removing a f ...