A C compressor causing P0AA6 code

My newly purchased 2010 Prius with 229,000 miles has a blown 40 amp fuse for the A C compressor. And, I was getting P0AA6 codes, yellow triangle and "Check Hybrid System". I bought a Vici 500 volt megohmmeter. The battery is O K. The motor/generaters are O K. I disconnected the cable going to the A C compressor. The fused side of the cable acted like charging a capacitor to > 20 megohms. The unfused side read 0 ohms with the Vici tester. The inverter reads 1.9 megohms.
I cleared the codes and did not reconnect the compressor cable. When I drove the car, there was no triangle or "Check Hybrid System".
For the time being, I want to drive the car without buying a new compressor. The inverter has an empty hole where the cable was plugged in. I worry about dirt entering the inverter. If I plug in the compressor cable at the inverter, will the triangle or the "Check Hybrid System" cause a problem? Would it be safe to unplug the high voltage cable at the compressor? I do not plan on turning on the A C controls on the dash.

 

Yes, I also did the math. That is a lot of power. Fuses are over-sized to eliminate nuisance fuse-blowing. They are mainly there to protect wiring or a stalled motor. And, the inrush surge current when the compressor starts is higher than when running.

I am wondering if I also need to replace the dryer and condenser at the same time as the compressor. Some recommend doing that because of air entering the system when the hoses are unscrewed. But, even if I have a new dryer, condenser and compressor, at some point I must open the end of the hoses, compressor, dryer and condenser before attaching the parts together. And air will enter!
If I can unscrew the hoses on the old compressor, mount the new compressor and re-attach the hoses very quickly, maybe I will only need to replace the compressor?
I am confused by some youtubes. I saw where some oil remains in the hoses. And, if I add the proper amount of oil to the compressor, then, there will be too much oil. But, nobody knows how much oil is in the hoses.

 

And the fuses cost $35 each.

 

I did not know that the electronics (other than the motor) were in the compressor. Interesting.
I did unplug the power cable from the compressor. The fault remained. The fault is on the low side (unfused). I tested the cable with my Vici 500 volt tester. It failed with the compressor unplugged. I am surprised. The cable is double insulated and insulation is cheap. And, why did my fuse blow? The fused side of the cable is O K. I might need to replace both the cable and the compressor.
I just retested with the 500 v Vici tester. I found that if I pull the connector fully away from the inverter, it checks good. Then, I found that the metal cover on the cable end is shorted to the power connector low side. see attached. Now I am trying to figure out if this short damaged the compressor or caused the fuse to blow.

 

The cable is defective. Poor design or poor quality control. It should have been hi-pot tested at the factory.
Replacing the cable appears to be another lengthy frustrating job. I might wrap the metal sleeve with electrical tape for now. See image of the metal shell and the metal sleeve that should be insulated from the wire.

 

I did wrap the sleeves with electrical tape. The electrical tape repair did not last, so I removed the metal shell for now. I ended up breaking the low voltage control connector at the compressor. I broke it when trying to remove it. What a terrible design! Is there a special tool to help remove the plug?
And, I found that the compressor is also shorted. I will need a new compressor and a new power cable. And, now, a new control signal connector at the compressor. ebay has them with a better design where I can push the catch and pull the plug at the same time.

 

The fuse was not installed. In the image, the metal shell (strain relief) is removed. The ohmmeter reads (almost) zero ohms. I was measuring the low (unfused) side. There is a metal sleeve (for strain relief) on each of the 2 power leads. Sorry that I did not get a better image. They should be insulated from the internal copper conductor wire. One is and one is not. Vibration and strain must have caused the partial short. The metal sleeves are sandwiched between the metal shell, which is bolted to the inverter cover. Thus, a leakage path exists to frame ground.
I was surprised and disappointed that the compessor is also bad. But, I double checked it.

 

Interesting! Shielded wires. The braid is attached to the metal sleeve. I can see that a center conductor short anywhere to the shield will cause my problem.
I have ordered a used compressor with a 6-month warrenty. And a manifold set and a high voltage cable.
I have watched hours of youtubes. Some take drastic shortcuts. I will replace the compressor, condenser, receiver/dryer and flush the hoses. If there is dirty conductive oil in the evaporator and expansion valve, I will flush those. I think that if I must take the dash apart, that will be the worst part.
O'Reilley has a rental pump that will pump down to 75 microns. Is this good enough? Typically they will go to 40 microns for a single stage pump.
Toyota recommends their oil at over $200 while I can buy Denso ND Oil 8 brand for $25 or Honda hybrid oil for $40. Must I really use the $200 oil?
Thank you for educating me.

 

I bought a can of Honda POE oil. I think that it will be fine.
I watched a youtube showing a Ford system being fixed. The factory manual said to add a filter to compressor input and liquid line to prevent damage unless all components are replaced. That seems like good insurance to me. Are these available for a Prius? Removing the evaporator is a lot of work. I can flush it, but that is no guarentee.
And, does the Prius use anexpansion valve or an orfice tube? And, will a vacuum pump that will only go to 75 microns be good enough?
Thank you for your patience with my many questions.

 

My pins have not corroded yet. I have been trying to think of a preventive measure to save the connector. I wonder if filling the compressor side connector (male pins) with plumber's grease. (silicone grease) It is not conductive and will not harm plastic or rubber parts. The contacts should make contact, I think. Or, how about a plastic bag wrapped tight with zip ties securing it?
I searched ebay for a Prius add-on in-line after-market freon filter without any luck.

 

Bingo! I want to clean my engine without worrying about ruining the connector. see attached

 

Thank you, Chap. This is what this grease is made for. I will use it on several connectors.