Rick's Free Auto Repair Advice

AC compressor oil

Use the correct AC compressor oil

Car and truck AC systems rely on circulating oil to lubricate the compressor. But just like engine oil, not all manufacturers recommend the same viscosity
AC compressor oil for their systems. For example, for R-134a refrigerants there are many different viscositites: PAG 46, PAG 100, PAG 150. A Sanden SD7H15 compressor requires SP-15 PAG oil. Sanden SD5H requires SP-20. Sanden compressors used in GM, Honda, and VW models specify SP-10.

Auto AC compressor oil PAG 46 oil

PAG-46 AC compressor oil

AC compressor oil PAG 46

PAG-46 AC compressor oil in pressurized can

AC compressor oil PAG 46

AC compressor oil with fluorescent dye

The DIY issue: Adding too much oil

Every time you lose refrigerant, you also lose a bit of AC compressor oil. So it’s common to see DIYers go overboard and add more oil every time the add refrigerant. But that’s self defeating many times. If you add too much oil, you wind up coating the interior fins with oil. That oil actually reduces heat transfer getting you warmer air and lower MPG.

Shops keep track of how much oil comes out when evacuating an AC system. They replace just that amount. But how are you supposed to know? Well, if your system is down a few ounces of refrigerant, you can safely add more refrigerant without adding any oil.

Flushing after replacing a major component

Many AC component manufacturers also recommend flushing the

flush AC system with AC flush kit

Flush with an AC compatible fluid and flush it.

entire system when you replace a major component, especially if you replace the compressor. Then, follow this charge to replace the oil with the correct amount:

Component     Amount Of Lubricant To Add

Accumulator               2 oz.

Condenser                   1 oz.

Evaporator                  2 oz.

Filter Drier                 1 oz

©, 2015 Rick Muscoplat

Posted on by Rick Muscoplat

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