Correct oil separation is the nuts and bolts of A/C service

Correct oil separation is the nuts and bolts of A/C service

Correct oil separation is the nuts and bolts of A/C service

Avoid costly damage

The fact that over 90 percent of today’s cars and commercial vehicles is fitted with an air conditioning system makes A/C service a reliable cash machine for automotive workshops. Air conditioner maintenance is not only a good basis for successful business operations, it also protects customers from costly repairs. With the correct amount of refrigerant in the system, the compressor is properly cooled and lubricated thanks to the oil contained in the coolant. If there is too little refrigerant in the circuit, though, the system’s core component – the compressor – cannot be cooled and lubricated sufficiently. Serious compressor damage and chip formation can be the results of this deficiency.

What actually happens inside the A/C service station during the service process?

Does refrigerant recovery inevitably lead to overcharging with refrigerator oil?

To avoid overcharging, service stations are fitted with an internal oil separator. Here’s in a nutshell how it works: The refrigerant is recovered from the A/C system via the hoses at the high-pressure and low-pressure sides. Simultaneously, the oil separator separates the refrigerant from the refrigerator oil. The refrigerant is then passed on to the internal compressor, fluidised in the internal condenser and finally returned to the internal refrigerant tank.

In the process the service unit records the refrigerant charging level – and also the amount of refrigerator oil leaving the oil separator after the recovery operation. The service station then returns the required amount of oil to the automotive air conditioner.

Why all of this?

Old OilThe mixture of refrigerant and oil is separated during the A/C service to prevent compressor hydrolock. Moreover, the refrigerant must meet the purity requirements according to the SAE 2099 standard after the recycling process. This goes for all air conditioners and A/C service stations, R 134a and R 1234yf alike. Service units for the “new” refrigerant are fitted with additional safety features – e.g. a ventilation system and a safety switch – to protect workshop staff at work. 

And here is the crux of the matter:

All A/C service stations featuring an integrated refrigerant analysis tool or a so-called refrigerant identifier have to be fitted with an additional oil separator upstream.

Refrigerant identifier have to be fitted with an additional oil separator upstream

ASC in Detail 1Why? As described earlier, every refrigerant recovery process will also mean that refrigerator oil is drawn out of the system. This is a fact that cannot be avoided. Some service units try to evade this situation by taking a gas sample from the low-pressure side of the vehicle. A widely held belief in the market is that refrigerant recovery at the low-pressure side will not cause “oil throw-out”. However, this is not true. Any oil entering the refrigerant analysis tool will cause irreparable damage to the infrared measuring chamber of the device; it is impossible to clean it away afterwards. The only alternative is to replace the whole unit, which can be a costly measure to take.

ASC in Detail 2Another common recommendation that doesn’t work is to clean up the hoses of the analysis tool from time to time. Besides the fact that this clean-up is often “forgotten”, it is not allowed to use aggressive cleaners inside the system. In the end, it is the workshop and the car owner who have to pay for it, because manufacturers give no goodwill warranty in case of improper use.

Therefore, A/C professionals are well advised to opt for the equipment offered by A/C specialist WAECO, because the gas analysis tools provided by the German company already come with an additional oil separator fitted upstream the analysis module.

For more information about the complete range of professional A/C equipment.

Pictures to download

Text to Download

ZIP archive

author posts

Professional standard

ASC by WAECO is, and has been for years, the abbreviation for excellent quality and cutting-edge technology in A/C service equipment. The series is constantly improved and complemented to meet future requirements. All ASC service units are state of the art and fully automatic

Be a successfull A/C professional

Use our comprehensive range of equipment for service and repairs on automotive A/C systems to make your company an efficient and successful A/C workshop. Polar bear Eddie supports you with useful information and advertising material that will keep you an Eddie nose length ahead of your competitors!


Dometic UK Ltd.
Dometic House, The Brewery,
Blandford St. Mary
Dorset DT11 9LS

Tel +44 (0) 344 626 0135
Fax +44 (0) 344 626 0143