Jun 18, 2021

How to check and fill automotive air conditioners using test benches and testers by MSG Equipment?

How to check and fill automotive air conditioners using test benches and testers by MSG Equipment?

Servicing automotive air conditioners requires the use of filling and diagnostic equipment.

Even a totally healthy air conditioner leaks – it’s unavoidable due to the small size of the refrigerant molecules and thus the high penetrating power of the substance. That's the amount of the leaked refrigerant that makes all the difference - 10% per year is the norm. So, it means that refilling the air conditioner once in two-three years is enough to avoid the trouble. 

Due to the design specifics, you cannot just add some amount of the refrigerant to the system – it is an accurate amount you should be filling in. The only possible way to do this is by pumping the system and weighing the agent. 

In the absence of other problems, a scheduled refill of an air conditioner is performed in the following order:

Step 1: AC system diagnostics

General diagnostics of an AC system is a must, even if everything seems to be good. Health assessment of the AC saves time and trouble as most car owners don't even remember when exactly was the last time the system was serviced.

The diagnostics include

  • checking the refrigerant type with a gas analyzer;
  • measuring the operating pressure in the system pipelines that reveals the system's condition and, whether the leak is within the norm or above it.

Step 2. Refrigerant evacuation

The refrigerant evacuation is performed with a special filling station for automotive air conditioners. After pumping, the machine will show the weight of the removed agent. This parameter allows us to understand if the leak is normal or excessive? Along with the refrigerant, the station will pump some amount of oil, which is usually 10-15 grams. More oil in the system signals some problems, and in that case, a comprehensive diagnosis is strongly recommended. 


Vacuuming is a time-consuming process. You'll need about 30 minutes to complete the procedure. A high vacuum will ensure filling the system with the necessary amount of refrigerant.   


Refilling the system doesn’t take much time. On average, we need 500 grams of refrigerant to fill one air conditioner. Apart from the refrigerant, we should restore the amount of oil evacuated from the AC system. Special colored dye is often added to the system to make it easier to detect potential leaks in the future. The use of modern filling stations makes the above procedures simple and easy to perform.

Step 5. Post-maintenance check

This is the last step of air conditioner refilling. We should start the engine, turn on the AC and set it to the lower temperature limit and the blower - to its maximum speed. Then we rev up the engine to 2500-3000 RPM and monitor the system operation. If the air in the cabin is cool and the AC compressor doesn’t work non-stop, we can conclude that the system is faultless. 

If a significant leak has been detected in the course of the system diagnostics, then it should be diagnosed once again - this time more comprehensively, which implies checking the compressor on test bench MS111 and localization of the leak. The further repair will depend on the AC compressor test results.

Equipment for AC systems and advanced training for repair technicians

Test benches and testers by MSG Equipment are efficient in providing AC accurate and timely diagnostics and repair.

  • Test bench MS111 assesses the technical condition of AC compressors. The bench is used for post-maintenance and pre-sale checks of compressors.
  • Pneumatic flushing stand for air conditioners MS101P cleans the AC pipelines from contaminations.
  • Tester MS121 checks electromagnetic clutches and control valves of AC compressors removed from vehicles.
  • Test bench MS112 is used for the health assessment of electric compressors of automotive air conditioners.

Not only does MSG Equipment manufacture state-of-the-art equipment for diagnostics and repair of automotive systems, but it also holds training courses for garage specialists at its own Training Center. Contact our managers to register for the course “Maintenance and repair of automotive AC systems”.   


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