High Voltage A/C Compressor Oil Issues

What if I used the wrong oil in a High Voltage Electric compressor?

Rotor on right, stator in housing. Prius II

Rotor on right, stator in housing. Prius II

If you accidentally add the wrong oil into an A/C system that uses high voltage to spin the compressor the manufactures all say the same thing. Replace every component. Period. Easy to say but what about the reality of the cost involved to the owner or the shop if it was their mistake? In the USA, where I live and work, there are over 2,100,000 hybrids and over 1,500,000 have high voltage compressors. This is the largest concentration of hybrids in the world. I come in contact with many A/C shop owners and mechanics. Here is what I have learned that did not come out of a book.

In the spring of 2007 a shop owner from Florida confessed to me after a hybrid class I was teaching that he had added ester oil into two Generation II Priuses (2004-2009) and didn’t know until I mentioned it in my class that is was a mistake. I asked him how long the universal oil (ester) was installed and he replied “it had been over a year for both”. I asked if these were good customers. He answered “I know them well”. If the Prius owners had a problem, it would make sense that at least one would have returned to complain. That was my first hint that maybe the OEM’s may just be playing it safe by requiring their own oil.

September of 2007 I had my first road test in a Chevy Tahoe 2 Mode hybrid. It was a press car that is loaned to the media before production. I asked lots of questions, one of which was “who makes the compressor?” The factory representative said she didn’t know. After much searching I found out it was Mitsubishi. The A/C warning label on the hood states that it requires ester oil, without further mentioning adding a specific type.  The Dodge Durango 2 Mode I drove in September of 2008 (since discontinued due to lack of funding) required ND-11. Not hard to figure out who supplied the compressor for the Dodge. As I asked some more questions, a good source told me “GM did not want to make a requirement for its dealers to have to buy oil exclusively from Denso”.   Mitsubishi evidently was OK with ester oil so GM went with them.

Between the 2 Priuses in Florida and the label under the hood on the GM about the oil required for the Mitsubishi high voltage compressor, looks like universal ester oil may be OK. My company, ACDC, is still researching this but it is looking like the OEM’s may be crying wolf on ester oil, but what about PAG oil.

In October of 2008 my 2004 Prius with 94,000 miles (about 150,000 kilometers) on the car was used once again for hybrid research.  Karl Matis, Vice President of HECAT, Inc. based in the USA agreed to come to our 5 day hybrid class and experiment with PAG oil in the ACDC company car. Before he arrived we ordered two used Denso compressors from a salvage yard, ND-11 oil, o rings, a desiccant bag for the dryer, and a service plug from a Toyota dealership. Karl shipped up a special A/C flusher and with the help of Jeff, an ACDC trainer, and a student they added PAG oil into a virgin system. The ACDC Prius A/C system has never been worked on. A base line was established for the A/C system as it was presented. The A/C system was working properly with readings of 130 p.s.i. on the high side and 30 p.s.i. on the low side. After evacuating the system 16 oz. of refrigerant was added with 1 oz. of the wrong type of oil “PAG” directly from the R&R machines automatic oil injector. Over a period of two days more and more PAG oil was added, each time by evacuating the system and after a total of 5 oz. of the wrong type of oil “PAG” was introduced the system still operated without any codes present. The only noticeable difference was the high side had higher pressures, but the system worked. This is not what we expected to see based on what we had read on Toyota’s webs site.

After expecting to see system shut down due to high voltage leaking at the compressors coils and trouble codes set we came to the conclusion that PAG is most likely a problem over time, how long we do not know but not immediately. If you add PAG oil and run the system you may be OK if you can properly flush out the entire system as we did with HECAT flusher and use factory oil (or universal ester? Keep reading). For now we had to replace the compressor, and we did with a used unit, because you cannot buy the service parts needed to repair the compressor.

The ACDC Prius now has 143,000 (was 94K when we tried to break it). The A/C is running fine, with the PAG oil flushed out and ND-11 inside (Now Supercool oil), still no codes. The experiment is over. It is possible to fix a contaminated system without replacing everything, but only if you have the right equipment.

Why do the OEM’s demand that their special oil is used? My guess is it helps keep warranty costs down, provides a base line for them to analyze a failure and satisfies the compressor manufactures, which are Denso and Sanden for now.

ACDC has been doing some research with SupercooL based in Florida. Paul Erdlich and Reijo Seppanen came to Massachusetts to take in our 5 day class (they paid their own way) in the fall of 2010 and also to teach ACDC and our students more about A/C oil. The same car you have been reading about (our 2004 Prius now with 115K miles) was once again subjected to more hybrid experiments. SuperCooLs Hybrid oil was replaced using a Hecat flusher and I am now driving across the United States of America testing that oil. I am already convinced that SupercooL has this figured out, so at this time we are recommending this oil as a replacement for factory oil.

Cut Away A/C Compressor Prius II

Cut Away A/C Compressor Prius II

Why do they require replacing everything in the A/C system if the oil is contaminated with ester or PAG oil?  That question most likely has to do with the first question and a lack of confidence in flushing machines and techniques (for which HECAT has the answers). If not for the cost why not replace everything?  Customers will rebel as they should!

These words; craftsmanship, pride, and individual worth are words I like. When a mechanic can take a broken, worn, or contaminated part and make it useful again, they themselves feel useful. That leads to pride of workmanship. The net effect is overall better work and higher self image.

So the next time you find contaminated oil in a high voltage A/C system, before you replace everything get in touch with me for support. I will add more data here as we learn more.

What type of solvent is used in the HECAT?

Although most flushing machines have fallen out of favor, the HECAT H-1000 flushing machine is gaining converts. It uses Honeywell’s Genesolv SF refrigerant/solvent, which stays in liquid form under light pressure as the machine causes it to pulsate through heat exchangers, hoses and even expansion valves. When the flush cycle is done, the H-1000 uses light vacuum to boil the solvent out of the system—no residue. The machine filters the solvent for reuse, over and over—no disposal.

Craig Van Batenburg

DO NOT USE Supercool Oil on Hyundai or Kia Hybrids as they have something new that is not compatible.