RX400h aircon issue

[Parrot of Doom]

So it's stopped working on my car, a 2005 model.  What I presume is the aircon compressor is buzzing when running.  Here's a video (the fan and engine are running, but I hope you can hear the buzz).

https://drive.google.com/file/d/1lGM0s0CaQeURnRMXoQzg9rGB8WNSoESE/view?usp=share_link

I know it's the aircon, because it stops buzzing immediately when I turn the AC off on the screen.

My question is, for anyone with experience of aircon faults, is this the kind of noise an aircon compressor might make if the system had a leak and was empty?  Or the noise an ac compressor might make if it were faulty and just not doing it's job?

[Herbie]

That sounds more like an electrical buzz to me so I would highly recommend you get the OBD codes read and see what's flagged up. Given that the aircon compressor is driven by a 500V 3-phase AC variable frequency motor you do not want to go poking around willy-nilly.

There should be a pressure sensor that will stop the aircon from functioning if refrigerant leaks out and pressure drops too far, so I don't think it'll be that the system is empty, but without the OBD codes all we can do is guess really.

[Parrot of Doom]

No codes from the car, nothing on the dash.  I only noticed it a few weeks ago but it was too cold to know if the AC was working or not.

 

I will double check.

[Parrot of Doom]

Nope, no codes logged.

[Herbie]

2 hours ago, Parrot of Doom said:

Nope, no codes logged.

Are you using Techstream or a generic code reader?

[Parrot of Doom]

Just a generic obd2 Bluetooth reader.  My usual garage don't do aircon so I'm going to nip to Kwik Fit to see what they say.  Apparently they don't charge for a quick look.

 

[Herbie]

1 hour ago, Parrot of Doom said:

My usual garage don't do aircon so I'm going to nip to Kwik Fit

From what I've read in here, as soon as you say it's a hybrid they'll run a mile and say that they don't deal with hybrids. However, if they do and if they say it needs regassing, make absolutely sure that they know to use ND11 oil instead of the PAG oil that conventional cars use.

The refrigerant gas is the same but the lubricating oil has to be ND11 or equivalent, which is a high dielectric oil that doesn't conduct electricity. As I said above, the compressor is driven by an electric motor and the windings of that motor sit in the oil for cooling purposes. PAG oil will damage the windings and result in insulation resistance breakdown, allowing the 500V to track to earth, which in the case of hybrid cars is the car body. There are inbuilt safety measures to avoid the body becoming live but if something were to go wrong.....

[Greisingel]

Anything on/in the AC fan, which invariably runs while AC on.

[Parrot of Doom]

System was empty, so they've refilled it and I'll have to keep my eye on it.  Working fine now.

[Parrot of Doom]

On 4/24/2023 at 2:04 PM, Herbie said:

From what I've read in here, as soon as you say it's a hybrid they'll run a mile and say that they don't deal with hybrids. However, if they do and if they say it needs regassing, make absolutely sure that they know to use ND11 oil instead of the PAG oil that conventional cars use.

The refrigerant gas is the same but the lubricating oil has to be ND11 or equivalent, which is a high dielectric oil that doesn't conduct electricity. As I said above, the compressor is driven by an electric motor and the windings of that motor sit in the oil for cooling purposes. PAG oil will damage the windings and result in insulation resistance breakdown, allowing the 500V to track to earth, which in the case of hybrid cars is the car body. There are inbuilt safety measures to avoid the body becoming live but if something were to go wrong.....

 

I'll bear this in mind for the future, thanks.

[Spock66]

Also it's best to leave the Climate Control on all the time as this helps keep the system lubricated and seals from drying out etc.

[Herbie]

2 hours ago, Parrot of Doom said:

 

I'll bear this in mind for the future, thanks.

Being as you've already had it done, if you get past the next 6 months without problems then you'll know they used the correct oil. If you start seeing the 'Check Hybrid System' message on the instrument panel and you get P0AA6 when you read the OBD codes, you'll know the likely culprit and where to start looking.

Glad you've got it sorted though and fingers crossed for you my friend.