COMPONENTS OF THE AIR CONDITIONING Troubleshooting Expansion valve

COMPONENTS OF THE
AIR CONDITIONING
Troubleshooting
 Expansion valve/orifice tube

 
Expansion valve auto
 
Expansion valve/orifice tube:
 
Expansion valve
The expansion valve represents the point of separation between the high pressure and lowpressure sections in the refrigerant circuit. It is installed in upstream of the evaporator. To achieve optimum cooling capacity in the evaporator, the refrigerant flow is controlled by the expansion valve depending on the temperature. As a result, complete evaporation of the liquid refrigerant is ensured and gaseous refrigerant arrives at the compressor only. Expansion valves may differ in their design.

How they work
   
The liquid refrigerant - arriving through the filter dryer from the condenser - flows through the expansion valve and is injected into the evaporator. The evaporating refrigerant releases evaporation cold. This causes the temperature to drop. To achieve optimum cooling capacity in the evaporator, the refrigerant flow is controlled by the expansion valve depending on the temperature. At the end of the evaporator, the refrigerant is transported through the expansion valve to the compressor. If the refrigerant temperature increases at the end of the evaporator, it expands in the expansion valve. This results in an increase of the refrigerant flow (injection quantity) to the evaporator. If the refrigerant temperature lowers at the end of the evaporator, the volume in the expansion valve decreases. As a result, the expansion valve reduces the refrigerant flow to the evaporator.

Effects of failure
A defective expansion valve can manifest itself as follows:
*    Poor cooling capacity
*    Failure of the air conditioning system

There are a number of possible causes of failure:
*    Temperature problems due to overheating or icing
*    Contaminations in the system
*    Leaks at the component or the connection pipes

Troubleshooting
The following test steps should be followed in the case of a malfunction
*    Visual inspection
*    Acoustic test
*    Check connection pipes for tight and correct fit
*    Check components and connections for leak-tightness
*    Temperature measurement on the line system
*    Pressure measurement with the compressor switched on and the engine running
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