WHY THE AC COMPRESSOR FINALLY DIED A PAINFUL DEATH

HISTORY
Well, I just decided to put this out here, perhaps it would help someone.

Recently, a client of mine, called and complained that each time, his Prius gen2 (with 330, 542miles), was recharged, it doesn't last long, before it starts loosing its cooling efficiency.

I had asked him to bring the car down to the shop, to have the system diagnosed. But each time he tells me he's on his way, he just didn't show up.

He uses the car, as a Taxi with Uber, and doesn't have that time. Well, according to him though.

Finally, car was brought to the shop, after it had spent close to a month, in his place.

DIAGNOSIS
1.Physically inspected the AC system, for signs of refrigerant leaks on the compressor, discharge hoses/tubing's, and all that.

There weren't any signs of leaks or wetness on those components.

That made us believe, we're fine with them.

2. Checked the AC cabin filter, it was terribly dirty, and had to replace em with a new one.

3. Readied the car, and put on the AC system. There was some silence.Only hot air was blowing through the vents.

4. Disconnected the service plug, and waited for some minutes for the HV battery to discharged to zero volts, before we commenced testing the orange cabling connected to the AC compressor. We did all that, to be certain, it wasn't a voltage supply issue it had.

This checked OK, with about 200+volts coming to the orange cabling.

5. After finishing the voltage supply tests, we concluded it was the compressor that was faulty.

SOLUTION
1. The entire AC system was overhauled.

The reason was because when the compressor was removed, IT HAD ALREADY BURNED OUT(See pictures).

¶compressor replaced with a used one
¶condenser and all discharge hoses
¶flush the entire system
¶vacuuming the entire system, after flushing with a compressed air
¶repalced the cabin filter

2/ Recharged the system using only R123 refrigerant, and ND11 compressor oil.

WHY DID THE AC COMPRESSOR BURNED OUT?
In order for me to investigate the reasons for this failed compressor, I had to teardown the electric compressor, to investigate what happened.

MY FINDINGS
1. Compressor had its windings shorted out.
Electric compressors don't get shorted out for nothing. Its either a non specified compressor oil was used, which resulted in the dielectric on the copper windings to short out, or there was an over or low voltage supply problem.

The AC compressor assembly is susceptible to heat, just like your car's HV battery.

The refrigerant and compressor oil, helps to cool it(the electric motor in it).

In this case, the real culprit why the compressor burnouts, was because the previous AC system tech, had no knowledge of hybrid system, and decided to use the wrong oil(ND8), instead of ND11, and then flushing the entire system to get rid of cross contamination.

Hybrid vehicles use a special kind of compressor oil, ND11, which is non conducting between the windings of the armature in the compressor casing.

They are quite different from the ND8 used on conventional AC system.

So, if you want your AC system to last longer, and probably, for ever lime the Prius, use recommended compressor oil for the AC system.

Using other PAC oil, would cause shorting of the internal windings, and poses a shock risks to you, or a technician working on the car.

PS: Used an electric filing machine to rip open the compressor for investigations.

The blackish stuff is the soot from the burnt out compressor insulation windings, and the wrong compressor oil.

Only give your car to a hybrid professional knowledgeable about electric compressors.

Carry out total system flush of the AC, to get rid of probable cross contamination from the previous wrong compressor oil

 

Mehn, dealership isn't an option. Even in the so-called dealerships, there aren't competent hybrid pros.

Some of the problems we ha e here with hybrid cars are just that owners try to look for cheaper means of fixing those cars, without thinking of the long-term consequences.

 

Noooo! The dude took the car to some AC guy whose got no knowledge on hybrids.

That's what happens over Herr with lots of folks. Just gambling with expensive stuff

 

Yeah, as that, lots of folks over here, even the dealerships cross contaminate compressor oils during such services without knowing.

I don't know about the USA, or some places though.



Dxta

 

PA: I forgot to upload these pictures after the write-ups.

Notice how the burnout looked like. Powedery, and kinda like soot from a diesel engine.


Dxta