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 AC compressor oil.
The DIY issue: Adding too much AC compressor 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
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