O-rings are used at every connection of the air conditioning system creating a sealed system. The seals can withstand variable or constant pressures, high and low temperatures, preventing the venting of the refrigerant into the atmosphere.
The most common causes of a car O-ring failure and A/C leaks are the following
- Incompatibility between the O-ring material and the fluid it is to seal.
- The wrong O-ring size.
- Improper O-ring installation.
- Gland or cavity deformation.
- O-ring dry installation or using the wrong type of lubrication
Car O-ring tools & installation
The use of the proper tools for O-ring installations are critical to avoid any damage to the O-ring surface. The use of sharp-edged tools, passing the O-rings over sharp threads, lack of lubrication and use of poor quality O-ring materials are the main causes of O-ring damage and possible air conditioning leaks. It is recommended the use of picks for removal & installation of the O-rings. Always lubricate the O-ring with the right type of oil and cover sharp threads before passing the O-ring over. Choosing the right size of O-rings for every application in the air conditioning system is crucial.
Where do most car AC leaks occur?
All sealed auto systems leak. Concentrate your efforts at car ac system connections and fittings as these are the most likely leak sites.
Every pressurized system leaks, because flaws exist at every joint fitting, seam, or weld. These flaws may be too small to detect with the best of leak detection equipment. But given time, vibration, temperature and environmental stress, these flaws become larger, detectable leaks.
It is technically incorrect to state that a unit has no leaks. All system has leaks to some degree. A sealed system which has operated for 10 years without ever needing a charge is called a tight system. The system still has leaks, but not enough leakage to read on a gauge or affect cooling performance. No pressurized system is perfect.
Refrigerant escapes at different times and at different rates. Leaks may plug, and then reopen under peculiar conditions. A leak is a physical path or hole , usually of irregular dimensions. The leak may be the tail end of a fracture, a speck of dirt on a gasket, or a microgroove between fittings
Types of auto ac refrigerant leaks
Types of leaks:
- Standing leaks
- Pressure-dependent leaks
- Temperature-dependent leaks
- Vibration-dependent leaks
- Combination-dependent leaks.
Passive leaks are leaks that can be detected while the unit is at rest of off. Standing leaks are the most common of all leaks.
Pressure dependent leaks are leaks can only be detected as the system pressure increase.
Temperature-dependent leaks are associated with the heat of expansion. They are usually due to high-temperature ambient air or condenser blockages or restrictions in the ac system.
Vibration dependent leaks only occur during a/c system operation. The mechanical strain of motion, rotation, refrigerant flow , or valve actuation are all associated with vibration-dependent leaks.
Combination dependent leaks are flaws that require two or more conditions in order to induce leakage.
How can I find where my AC is leaking?
Electronic Leak detector procedure according to EPA:
When using an electronic leak detector ,always follow the manufacturer’s operation instructions. In addition to the manufacturer’s instruction, the following should be observed
- Always leak test with the engine off
- Only a small amount of refrigerant is required to perform a leak test. A gauge reading of 50 psi is all that is needed. At temperatures below 50 F ,leaks may not be measurable , since 50 psi may not be attainable.
- To avoid contaminating the tip of your leak detector, remove excessive dirt from suspected leak areas. Do not use cleaners or solvents, your detector may be sensitive to their ingredients.
- Visually inspect the system , and look for signs of air conditioning oil leakage , damage , and corrosion on all lines, hoses and components . Each suspected area should be carefully checked.
- Follow the system around in a continuous path to ensure that no areas are missed. If a leak is found , continue to check the remainder of the system for additional leaks.
- At each area checked , move the probe tip around the location 1” per second while holding the probe no more than ¼ inch above the surface of the area being leak checked.
- To verify an apparent leak, blow shop air into the area of the suspected leak to clear any refrigerant that may linger and repeat the leak check
An alternative method of leak testing is to use Nitrogen to pressurize the system, then pin-point leaks with a soap and water solution.
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