29/04/2015

A/C Systems

Leaks in Car A/C

Figure shows the major sources of refrigerant leaks according to car manufacturers. At most 10 to 30 gr of refrigerant loss from the compressor shaft is widely accepted to be inevitable. 42 to 83 gr of refrigerant loss (10 to 20 gr from the hose system, 2 to 3 gr from each o-ring) is accepted to be “normal” for every year of operation.
In the newly developed air conditioning systems dryer-condenser and expansion valve-evaporator are manufactured together to reduce connections points thus reducing leak (52 gr leak yearly).
Source: Emission of Refrigerant R-134a from Mobile Air-Conditioning Systems, Dr. Winfried Schwarz.

1. EVAPORATOR
2. COMPRESSOR
3. CONDENSER
4. DRYER
5. EXPANSION VALVE

How Air Conditioning System Works

Refrigerant is pressurized using the compressor. As the refrigerant’s pressure and temperature rises, it turns into liquid while passing through condenser at approximately 60°C. When the car is moving condenser is cooled by air flowing through, other times it is done by condenser fan. Pressurized liquid refrigerant passes through the expansian valve, expands and loses pressure. In the evaporator, liquid refrigerant vaporizes and absorbs heat. Evaporator and surrounding area cools down from “-10°C” to “-18°C”. The evaporator fan controlled by the driver pushes the cool air into the car. The cycle repeats itself when the refrigerant turns into liquid again.

Nitrogen (N) Usage in Car Air Conditioning Systems

Nitrogen gas gives perfect results on air conditioning systems. Nitrogen is a dry and inert gas which is cheap and easily procurable. Pressure regulator is required to keep pressure under control. Suitable equipment can be found in stores that sell welding equipment. You will also need conversion unions for connection to the existing air conditioner manifold.
Nitrogen gas makes it easier to find refrigerant leaks.
When searching for leaks under pressure, pressurized air should not be used which contains moisture that harms air conditioning system.
Nitrogen dries air conditioning system and reduces vacuum duration
Nitrogenation before filling the system with refrigerant is an effective method in terms of drying and flushing. In order to do that, one edge of the air conditioning system is left open to the atmosphere. Other ending is tied to ac service manifold and nitrogen tube, then pressurized gas is sent to the system. Doing so will remove the moisture in the system. Another advantage of using nitrogen is reducing vacuum duration in deep levels.
Source:  www.autoacsystems.com