Leak Testers for Automotive Air Conditioning Systems

Frequently Asked Questions About Leak Testing of Vehicle Air Conditioning Systems

A reliable leak test helps detect refrigerant leaks and pinpoint the exact location of leaks in the air conditioning system. Depending on the air conditioning system and the test requirements, nitrogen, formier gas, and electronic leak detection technology can be used.

• When should a car's air conditioning system be checked for leaks?

  A leak test is particularly useful or necessary when:

  • an unusually high refrigerant loss has been detected,
  • the air conditioning system is empty or nearly empty,
  • pipes or components have been repaired,
  • the compressor, condenser, or other components have been replaced,
  • a leak is suspected,
  • the system needs to be tested before being refilled.

  The specific testing procedure depends on the vehicle, the refrigerant, and the manufacturer’s specifications.

• How is an air conditioning system tested for leaks?

  The properly prepared air conditioning system is pressurized with a test gas via appropriate connections.
  
  The system is then checked to ensure that the built-up pressure remains stable over the specified period.
  
  If the pressure drops more than the permissible limit, a possible leak must be assumed.
  
  The leak can then be located, for example, using tracer gas and an electronic leak detector.

• What gas is used to test the airtightness of an air conditioning system?

  Suitable nitrogen can be used for the pressure test.
  
  Forming gas is suitable for additional leak detection.
  
  In standard air conditioning leak detection, forming gas consists of nitrogen with a small amount of hydrogen. The hydrogen can be detected using a suitable electronic leak detector.
  
  The test gas must be suitable for the intended procedure and air conditioning system.

• What is the advantage of a forming gas leak detection test?

  Forming gas not only makes it possible to detect a pressure loss but also to pinpoint the exact location of the leak.

  The hydrogen component of the test gas consists of small molecules and can escape at leak points.

  A specially designed electronic leak detector detects the escaping gas.

  This allows for the targeted detection of leaks, for example, at:

  • Pipe connections
  • Screw connections
  • Hoses
  • Condensers
  • Evaporator connections
  • Compressor connections
  • Service connections
• What is the difference between a pressure test and an electronic leak detector?

  The pressure test shows whether the system maintains the test pressure.

  It first answers the question:

  Is the air conditioning system leak-free?

  An electronic leak detector is then used to locate the leak.

  It answers the question:

  Where is the leak?

  For a systematic diagnosis, both methods can therefore be combined..

• What is the role of the ELS 04 in air conditioning system inspections?

  The ELS 04 is an electronic gas leak detector and can be used to detect leaks in forming gas.
  
  The device reacts to the hydrogen contained in the forming gas.
  
  Any detected gas concentration is indicated by visual and audible signals.
  
  The 500 mm long gooseneck makes it easier to inspect hard-to-reach areas.

• Is the ELS 04 a refrigerant leak detector for R134a or R1234yf?

  The ELS 04 is used in air conditioning diagnostics, particularly in conjunction with formier gas.
  
  It detects the hydrogen content of the test gas rather than specifically identifying the refrigerant R134a or R1234yf.
  
  This makes it a suitable complement to a leak test using formier gas.

• How long should a leak test take?

  The required test duration depends on the vehicle, the test procedure, and the manufacturer’s specifications.
  
  For a quick test, a relatively short observation period may be sufficient.
  
  When searching for small or gradual pressure losses, a significantly longer test duration may be necessary.
  
  The Leitenberger SLD 01, for example, allows for documented test durations ranging from 10 minutes to 24 hours.

• Why are long-term leak tests useful?

  Very small leaks may cause only a very slight drop in pressure within a few minutes.
  
  During a longer test period, such a change becomes more clearly visible.
  
  A long-term test can therefore be particularly useful in cases of gradual refrigerant loss.
  
  Temperature changes during the test must be taken into account when evaluating the pressure curve.

• Why should temperature be taken into account during a pressure test?

  The pressure of a confined gas changes with temperature.
  
  If the system cools down during the test, the displayed pressure may drop even though there is no leak.
  
  If the system heats up, the pressure may rise accordingly.
  
  Therefore, significant temperature changes should be taken into account when interpreting a pressure curve.

• What is the advantage of a leak tester that generates a test report?

  An integrated test report provides traceable documentation of the test procedure.

  This can be particularly helpful for:

  • Workshop documentation
  • Customer information
  • Warranty claims
  • Quality control
  • Long-term testing

  The Leitenberger SLD 01, for example, features an integrated report printer and a real-time clock.

• What is the measurement accuracy of the SLD 01?

  According to the device specifications, the Leitenberger SLD 01 operates with a measurement accuracy of 0.5 percent and a pressure display with a resolution of 0.01 bar.
  
  It allows for testing of both the high- and low-pressure sides and can document tests lasting between 10 minutes and 24 hours.

• What is the difference between SLD_01_LR1 and SLD_01_LR2?

  Both versions include the digital leak tester with a built-in test report printer and connections for R134a and R1234yf.
  
  The SLD_01_LR2 also comes with the ELS 04 electronic leak detector.
  
  This makes this version suitable for both pressure testing and subsequent leak detection using forming gas.

• What is the difference between KLDS 05 and KLDS 06?

  The KLDS 06 is designed for leak testing air conditioning systems using R134a and R1234yf.
  
  The KLDS 05 also includes the necessary connections for R744 and CO₂, respectively.
  
  This makes the KLDS 05 particularly suitable for repair shops that service R744 air conditioning systems in addition to traditional R134a and R1234yf vehicles.
  
  The KLDS 06 can be retrofitted for R744.

• Why does R744 require special testing equipment?

  R744 operates at significantly higher pressures in automotive air conditioning systems than R134a or R1234yf.

  Therefore, all pressure-bearing components of the test setup must be specifically designed for the corresponding pressure ranges.

  These include, for example:

  • Pressure reducers
  • Pressure gauges
  • Hoses
  • Couplings
  • Valves

  The KLDS 05 features separate connections and safety components for the various air conditioning systems.

• Can a leak tester designed for R134a also be used automatically for R1234yf?

  Not automatically.
  
  R134a and R1234yf air conditioning systems use different service ports or couplings.
  
  The test unit must therefore be equipped with the appropriate ports designed for each system.
  
  Leitenberger offers systems that already include both types of ports.

• What is the correct test pressure for a vehicle's air conditioning system?

  There is no standard test pressure for all air conditioning systems.

  The permissible test pressure depends, among other things, on:

  • Vehicle
  • Refrigerant
  • System design
  • High- or low-pressure side
  • Component being tested
  • Manufacturer’s specifications

  The maximum operating or measurement range of a test device must not be confused with the vehicle’s permissible test pressure.

  The vehicle manufacturer’s technical specifications always take precedence.

• Can a vacuum hold test replace a pressure test?

  Not in every case.
  
  A vacuum test subjects seals and components to forces in a different direction than a pressure test using overpressure.
  
  Therefore, a system may appear to be leak-tight under vacuum but still behave differently under overpressure.
  
  The procedure required after a repair depends on the vehicle manufacturer’s and repair specifications.

• Can an air conditioning system be tested for leaks using a contrast agent?

  UV contrast agents can be used in certain refrigeration systems in accordance with the manufacturer’s specifications.
  
  However, a known leaking system should not be filled solely with refrigerant in order to subsequently search for the leak by observing escaping refrigerant or contrast agent.
  
  Methods using nitrogen and formier gas are available for targeted testing of a prepared or empty system.

• What safety rules apply when performing a pressure test on an air conditioning system?

  During pressure testing, it is essential to adhere to the permissible system pressures and equipment specifications.

  In particular:

  • Use only suitable test gases
  • Set the pressure regulator correctly
  • Use only hoses and couplings rated for the pressure
  • Do not exceed maximum system pressures
  • Build up and release pressure in a controlled manner
  • Inspect connections before testing
  • Use personal protective equipment

  For R744 systems, special safety requirements must be observed due to the higher pressure levels.