Ireland's Publication for the refinishing & associated Industries

A/C Compressors: Why the right oil matters

DENSO Aftermarket’s Senior Technical Engineer Gerard Magielsen reveals why the wrong A/C Compressor oil is the biggest cause of product failure – and offers an essential A/C checklist

Maintenance and repair of automotive air-conditioning (A/C) units, either manually or automatically controlled, represent a real expansion opportunity for garages and workshops.  In-depth technical knowledge of A/C systems, common faults, recommended components and oils are all essential to achieve customer satisfaction and build return business.

Central to this technical know-how is a comprehensive knowledge of compressors.  This is because 99.9% of all compressor problems are not related to product failure, but from a poor understanding of A/C system operation, maintenance and repair.

As one of the world’s leading suppliers of A/C compressors for automotive applications, DENSO knows these units better than anyone.  An original equipment pedigree and decades of research and development, mean that DENSO is uniquely placed to offer expert, practical advice on A/C compressor replacement and servicing.  We actively support customers through a series of training initiatives in selected regions to inform and train garages on car A/C service, compressor installation and repair procedures.

A key part of this support includes the launch of a new compressor installation guide, which is attached to every DENSO Compressor sold. But there is one aspect in particular that causes the majority of avoidable A/C Compressor problems: the oil.

Universal oil: a key cause of compressor failure

Compressors are vital to a vehicle’s A/C system; compressing the low temperature, low pressure gaseous refrigerant from the evaporator, into a high temperature, high pressure gaseous refrigerant, and discharging it to the condenser.

Oil in the A/C system is essential, primarily to lubricate moving parts, i.e. the compressor and the expansion valve needle. It also enables heat to escape from the compressor. As with refrigerant, oil in the A/C system must retain its chemical stability.

However, it is vital to choose the right oil for the job. Insufficient lubrication due to universal oil is the second most frequent reason for A/C compressor damage and failure. Analysis of DENSO A/C Compressor warranty claims for 2012 showed that in 24% of cases, garages did not use the correct PAG-oil needed for DENSO A/C Compressors.