AC for hybrid and electric vehicles

[JimPghPA]

I saw something interesting about the AC systems on hybrids and electric vehicles a couple of weeks ago, I think it was on one of Scotties YouTube videos but I can't remember for sure.

The AC on hybrids and electric vehicles has a compressor that shares it oil with an electric motor that drives it. If the AC system of a hybrid or electric vehicle is serviced using a refrigerant drain and charge system that has previously been used to service an AC system on a conventional gas powered vehicle then a small amount of impurities from the small amount of oil that got into the drain and charge system from it being used on a conventional system will contaminate the oil in the compressor and electric motor so that the oil no longer is non-conductive. This caused the electric motor to short out and fail.

 

[LotI]

Rule number 1, don't watch "Scottie's YouTube videos".

Rule number 2, see #1 or else you will go blind and get night vision lockjaw!

 

[bullwinkle]

The easy answer would be-use virgin non-recycled refrigerant to recharge those hybrid A/C systems. Not sure what would be special about regular automotive refrigeration oil that would short out an electric motor? Regular A/C hermetic compressors always have the motor inside with the compressor head, and they don't (normally) short out.

 

[JimPghPA]

Imagine having to replace the entire AC system is such a vehicle because the contamination would get into every part of the system and just replacing the compressor with built in electric motor would only set thing up to go bad again because of the contamination that by then had got into all parts of the AC system.

 

[mk378]

Why would the oil in a conventional system be less pure than that in an electric system? If a mechanic thinks that a system is contaminated he'll send the customer away rather than ruin his expensive machine.

 

[The Critic]

I don't know where Scottie gets this info from.

The electric a/c compressors use a special oil. Yes, the oil is non-conductive and you cannot contaminate the oil with conventional PAG oil. The compressor is electrically connected to the HV Battery but there is no connection between the electric drive motor and the a/c system; that is baloney.

 

[itguy08]

I don't know who Scottie is but this is true - from the MACS themselves:
https://macsworldwide.wordpress.com...echarging-ac-systems-on-hybrid-vehicles/

 

[Chris142]

The problem is the PAG oil that's used in every other car. They say that just a small amount of PAG oil in the valves,hoses etc will short out the hybrid parts. Must use a dedicated ac machine for hybrids or one that can flush its lines and other parts.

 

[nthach]

xHEV/BEV compressors are the automotive cousin of a hermetically-sealed HVAC compressor that's used on refrigerators/freezers, portable AC units and small(home)-medium sized HVAC. They use POE oil that's similar to what's used in stationary HVAC and refrigeration(Emkarate RL) but not quite the same as "universal" ester oil for mobile HVAC.

Denso is tight-lipped about the composition of ND Oil 11, the stuff in the aftermarket seems to be repackaged Emkarate RL68 or Solest oil. There was some European firm saying the Denso stuff has a 50kV dielectric value, while stationary HVAC has 30kV.

 

[PandaBear]

Originally Posted by LotI
Rule number 1, don't watch "Scottie's YouTube videos".

Rule number 2, see #1 or else you will go blind and get night vision lockjaw!


This. That guy is a fraud and should be avoided (i.e. washing the CAT in detergent).

Hybrid car / EV's AC is running off / can be running off electric motor / battery, that's actually good because you are not forced to run the engine with the AC, and you can run it at a speed you need for the cooling load, instead of using a clutch to cycle it on and off.

My wife love to park the car and keep the AC on, with no engine running until the battery is low. It is actually very nice and still fuel efficient.

 

[The Critic]

Originally Posted by itguy08
I don't know who Scottie is but this is true - from the MACS themselves:
https://macsworldwide.wordpress.com...echarging-ac-systems-on-hybrid-vehicles/

Yeah, I misread the original post. The compressor does share oil with the electric drive motor and therefore it needs the special oil. For some reason, I associated drive motor with the transaxle....read too quickly.

 

[JHZR2]

Originally Posted by nthach


Denso is tight-lipped about the composition of ND Oil 11, the stuff in the aftermarket seems to be repackaged Emkarate RL68 or Solest oil. There was some European firm saying the Denso stuff has a 50kV dielectric value, while stationary HVAC has 30kV.


Given that the dc bus on an xEV is like 300v, either would do if that was the case. There must be something else to it.

Originally Posted by PandaBear


My wife love to park the car and keep the AC on, with no engine running until the battery is low. It is actually very nice and still fuel efficient.


It's kind of nice. The engine still has to start and short cycle/low load on an HEV every few minutes. The energy consumed by the battery or the engine to run the compressor is the same. The energy balance still requires the same amount of energy to do the cooling.

The trick is if it could actually be 10-15 minutes of ops and then one would be driving away anyway. Which is why I'm an advocate of phevs over hev and ev.

 

[nthach]

Originally Posted by JHZR2

Given that the dc bus on an xEV is like 300v, either would do if that was the case. There must be something else to it.

The AC compressor is usually driven off the 200V DC battery, it has a separate inverter(at least on Toyota-based hybrids). The hybrid motors run off a 500-700V AC bus - the voltage is boosted with a buck-boost transformer in the main inverter.

The compressors used in commercial HVAC and refrigeration run off 230V-460V AC. Someone should send in a sample of the Denso stuff and the Emkarate for testing.