Mazda CX-5 Service & Repair Manual: Expansion Valve

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.