Don’t overlook compressor oil, reminds DENSO
Without oil in the air conditioning (A/C) system, the compressor will seize. This makes oil essential in the A/C system. Just as modern engines requires oils with specific formulations, A/C systems must also have the correct specification of compressor oil to make sure the compressor will operate under all circumstances.
To underline the importance of this message, DENSO, an AC pioneer and the preferred supplier to many VMs globally, is drawing attention to the fact that it has three formulations of premium quality oil in its AC lubricant range. These are specifically designed to suit the requirements of its various compressors, all of which are pre-filled with the correct specification of oil before their shipment, and is the only oil that will not invalidate their warranty.
Looking at the three oils individually is important because, despite opinions to the contrary, not all oils and refrigerants can mix, which casts doubt on the efficacy of an ‘universal’ AC oil. At this point it is worth reminding technicians that refrigerants must also not be mixed.
DENSO ND-oil 8 is a PAG 46 (this indicates its base oil type and viscosity) formulation and is designed for mechanical compressors using R134a refrigerant.
DENSO ND-oil 11 is a POE formulation, which is specifically designed for electrically driven compressors using either R134a or R1234yf refrigerant.
DENSO ND-oil 12 is another PAG 46 formulation, but with specific additives and is for mechanical compressors using either R134a or R1234yf refrigerant.
In addition to the correct formulation of oil, when installing a replacement compressor it is vital to have the right amount of oil in the AC system.
If, when the old compressor was removed, the system has been flushed, the new DENSO compressor can be installed directly, but don’t forget to check if the pre-fill quantity matches with the VM’s data.
If however, flushing is not required, technicians should use the following calculation to determine the correct amount of oil to drain from the new DENSO compressor:
A = Total oil amount in the new compressor
B = Amount of oil drained from the old compressor
C = Amount of oil to remove from the new compressor
As an example, if the total amount of oil in the new compressor is 120cc (A), and the total amount drained from the old compressor is 50cc (B), then the amount of oil to remove from the new compressor is A-B (120-50), in this case 70cc (C).
However, for some applications it is necessary to add oil; for example, where there is one and the same part number for single and dual evaporator, or when the oil quantity of the new compressor differs from the VMs specification. If this is the case, technicians should check the VM data to confirm the correct oil amount. However, oil should never be added to the compressor; instead, it should always go into the condenser, receiver drier or evaporator.
After installing a new compressor, it is essential to ‘run it in’, the purpose of which is to correctly distribute the oil to prevent damage immediately after the new component is fitted.
Check the Compressor Installation Guide and our videos for more detailed information.
Installation Guide: https://assets.denso-am.eu/production/attachments/AC-Compressor-Installation-Manual-multilingual.pdf
Videos:
How to balance the compressor oil level: https://youtu.be/bd2QYbO1OEw?si=LlZXhuBB0fgPQM0J
How to replace and AC compressor: https://youtu.be/0_Gc9ikTkOY?si=uOcJ2aff38Ew43mM
Further details of the DENSO Aftermarket programme are available online at: www.denso-am.eu