Avoid costly air con service damage with correct oil separation

Dometic Group offers essential air conditioning service advice for technicians

Avoid costly air con service damage with correct oil separation
Correct oil separation is the nuts and bolts of air conditioning service, Dometic say.

More than 90 per cent of today’s cars and commercial vehicles (CVs) are fitted with an air conditioning system, making air conditioning servicing 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.

In a press release, Dometic Group said: “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, 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.


“To avoid overcharging, service stations are fitted with an internal oil separator.

“The refrigerant is recovered from the air conditioning 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.”

Compressor hydrolock

The mixture of refrigerant and oil is separated during the air conditioning service to prevent compressor hydrolock.

The refrigerant must meet the purity requirements according to the SAE 2099 standard after the recycling process.

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.

Dometic Group adds: “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.

Cleaning hoses

“Another 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, air conditioning professionals are well advised to opt for the equipment offered by air conditioning 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, click ‘more details’ below.

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