Rx400h ac compressor

aeroelastic · June 20, 2020

Hi all, was doing my engine radiator change, then noticed that the Rx400h AC compressor does not have a drive belt connected to the engine crank shaft as all my other non hybrid car.
Run by the electric motor I presumed?
If I were to top up the freon gas, is it still the same procedure as the normal engine driven compressor? Is there any specific step/precautions?
thanks

Herbie · June 20, 2020

STOP! Cease and desist! Step away from the compressor! :laughing:

You're right, it's driven by an electric motor but the main concern is that the motor windings are immersed in the oil for cooling purposes so it has to be a special oil that is not electrically conductive. If I remember right it's ND11 oil instead of the normal PAG oil but I'm sure someone else will confirm that.

If you search the forum you'll find a right tale of woe from one of our fellow members.

He'd only had the car a couple of weeks and the aircon wasn't getting as cold as it should, so he went back to the trader he got it from. They said something along the lines of, "Our guy is on leave so just take it to Halfords and we'll pay the bill".

Unfortunately, instead of doing a full aircon service, ie, refrigerant out, pull a vaccuum to test for leaks etc., etc., with a proper aircon machine, the Halfords drone just grabbed a DIY top-up can off the shelf and squirted said gas into the system.

Even the slightest drop of PAG oil in an ND11 system can cause electrical problems and if I recall correctly it ended up with compressor, dryer and a couple of other components being replaced - although I may not have that correct as I've drunk far too many beers during lockdown to be sure it's accurate! :laughing:

If it's not getting cold enough or there's some other reason why you think it needs regassing, my advice would be to take it to a proper aircon specialist and let them sort it.

aeroelastic · June 20, 2020

Thanks for the heads up, will check around and see which specialist is aware of electric compressor ac stuff. Won’t be going to Halfords. Not to be messed with seems like...

iwonder · June 20, 2020

You can top up with r134a gas. Just make sure there is no oil included in the top up bottle.

Herbie · June 20, 2020

26 minutes ago, iwonder said:

You can top up with r134a gas. Just make sure there is no oil included in the top up bottle.

I didn't know that, I thought they all had oil in.

Mind you, if it needs topping up then something must be wrong somewhere so it may be as well to go to a specialist anyway. We had a Nissan Maxima QX for best part of 10 years and the system ran just as cold (very cold) as the day we got it, so no top-ups or any other work needed doing at all.

steve2006 · June 20, 2020

Same here, 25 years old and still ice cold with nothing done.

Britprius · June 20, 2020

Save yourself a fortune. For R134a top up purposes Go to B&Q and buy a can of Rothenburger pipe freezer in a red aerosol. This is the stuff plumbers use to freeze a pipe to cut it without draining the water. It is pure R134a. The ROHS compliance certificate for this product can be seen on line. At around £17 for a very large can.

I know I'm going to be shot down in flames with things like this is illegal, but think about this. Plumbers use this all the time to just squirt on a pipe in the open atmosphere. You are putting it into a sealed system.

John.

Herbie · June 20, 2020

1 hour ago, Britprius said:

I know I'm going to be shot down in flames with things like this is illegal

I'll not shoot you down in flames for that John, but I still think there must be something wrong with any system that needs to be topped up so an investigation by a specialist would be money well spent.

Britprius · June 20, 2020

18 minutes ago, Herbie said:

I'll not shoot you down in flames for that John, but I still think there must be something wrong with any system that needs to be topped up so an investigation by a specialist would be money well spent.

If an AC system has a major leak I totally agree with you.

If however you have a system like mine that has a minor leak "needs topping up about every 3 years not totally re filling" you can spend a lot of money chasing a leak that is impossible to find. I have put dye in my system, and that does not show the leak.
So what I am saying is it depends on the rate of leakage, and not on loosing some gas over a long period.

My wife has a Toyota Aygo from 2006 still only 70,000 miles. The AC has never been topped up, and works fine. But still if I take it in for service the dealer will push for an "AC service". The AC filter is part of the normal service so what else are they going to do. Are they going to draw out the gas that has nothing wrong with it creating a vacuum in the system reversing the pressure on seals that are 16 years old, and refill with fresh gas reversing the pressure again? For no reason. I see this as more likely to cause a leak. If it ain't broke don't fix it.

John.

PCM · June 21, 2020

I think an AC Service is: switch it on, is it cold?

Then run one of the £7 aerosols through it.

That'll be £35 please...

aeroelastic · June 21, 2020

10 hours ago, Britprius said:

If an AC system has a major leak I totally agree with you.

If however you have a system like mine that has a minor leak "needs topping up about every 3 years not totally re filling" you can spend a lot of money chasing a leak that is impossible to find. I have put dye in my system, and that does not show the leak.
So what I am saying is it depends on the rate of leakage, and not on loosing some gas over a long period.

My wife has a Toyota Aygo from 2006 still only 70,000 miles. The AC has never been topped up, and works fine. But still if I take it in for service the dealer will push for an "AC service". The AC filter is part of the normal service so what else are they going to do. Are they going to draw out the gas that has nothing wrong with it creating a vacuum in the system reversing the pressure on seals that are 16 years old, and refill with fresh gas reversing the pressure again? For no reason. I see this as more likely to cause a leak. If it ain't broke don't fix it.

John.

Mine is probably similar, a very slow leak. I bought the Rx400h last year after summer so ac isn’t really critical, but with some of the warm days now it did show some different. I have 2 other cars, one is a 24 year old Toyota Prado which I normally just top up the r134 myself. For the Rx400h, I noticed That there is some dark stain around the low pressure ac connection to the ac condenser While replacing my Radiator, which suggested -a seal slow leak. The ac still blow cold air at high speed, not around town, just takes a while to get it to blow cold, which to be honest is not a problem. I was just curious and realising that the car Rx400h compressor is different hence put a question is this forum. But thanks for all the input, won’t be doing anything immediately I think.

when you said ac filter you mean the drier bottle? That seems to be integrated as part of the ac condenser in the Rx400h.

Britprius · June 21, 2020

30 minutes ago, aeroelastic said:

Mine is probably similar, a very slow leak. I bought the Rx400h last year after summer so ac isn’t really critical, but with some of the warm days now it did show some different. I have 2 other cars, one is a 24 year old Toyota Prado which I normally just top up the r134 myself. For the Rx400h, I noticed That there is some dark stain around the low pressure ac connection to the ac condenser While replacing my Radiator, which suggested -a seal slow leak. The ac still blow cold air at high speed, not around town, just takes a while to get it to blow cold, which to be honest is not a problem. I was just curious and realising that the car Rx400h compressor is different hence put a question is this forum. But thanks for all the input, won’t be doing anything immediately I think.

when you said ac filter you mean the drier bottle? That seems to be integrated as part of the ac condenser in the Rx400h.

No I meant the cabin filter. Sorry I did not make that clear. Changing the drier sock filter requires emptying the system of gas.
If your car only gets cold at speed check that the radiator fans come on when the AC is turned on as the system requires that the rads have air flow through them at low road speeds.

John.

aeroelastic · June 21, 2020

5 minutes ago, Britprius said:

No I meant the cabin filter. Sorry I did not make that clear. Changing the drier sock filter requires emptying the system of gas.
If your car only gets cold at speed check that the radiator fans come on when the AC is turned on as the system requires that the rads have air flow through them at low road speeds.

John.

Yeah checked the ac fan, it comes on as soon as the ac is pressed.

to reiterate what Herbie says:

https://www.google.co.uk/amp/s/macsworldwide.wordpress.com/2012/03/30/use-caution-when-recharging-ac-systems-on-hybrid-vehicles/amp/

Britprius · June 21, 2020

46 minutes ago, aeroelastic said:

Yeah checked the ac fan, it comes on as soon as the ac is pressed.

to reiterate what Herbie says:

https://www.google.co.uk/amp/s/macsworldwide.wordpress.com/2012/03/30/use-caution-when-recharging-ac-systems-on-hybrid-vehicles/amp/

Yes I do know about the importance of using the correct oil. In fact it was me that bought it to the attention of the forum having discovered the problem in 2004 while belonging to the Prius Chat forum "hence my tittle Britprius".
The Prius uses the same AC system as all the other Toyota/Lexus hybrids employing an electric motor driven compressor. PAG oil used in normal AC systems is electrically conductive, and since the hybrid motor compressor actually runs, and is cooled by the oil it is imperative the oil acts as an insulator. The compressor motor runs at around 500 volts, and any current leakage to ground is detected, and shuts down the car completely for safety reasons.
The reason for using an electric motor is that with a hybrid the engine may turn off at any time. If the compressor was engine driven this obviously would stop working. A number of other systems on the car also have to operate along the same lines for the same reason such as the power steering, brake assistance, and even the cabin heater hot water supply from the engine. No engine no hot water pumped to the heater.

John.

aeroelastic · June 21, 2020

40 minutes ago, Britprius said:

Yes I do know about the importance of using the correct oil. In fact it was me that bought it to the attention of the forum having discovered the problem in 2004 while belonging to the Prius Chat forum "hence my tittle Britprius".
The Prius uses the same AC system as all the other Toyota/Lexus hybrids employing an electric motor driven compressor. PAG oil used in normal AC systems is electrically conductive, and since the hybrid motor compressor actually runs, and is cooled by the oil it is imperative the oil acts as an insulator. The compressor motor runs at around 500 volts, and any current leakage to ground is detected, and shuts down the car completely for safety reasons.
The reason for using an electric motor is that with a hybrid the engine may turn off at any time. If the compressor was engine driven this obviously would stop working. A number of other systems on the car also have to operate along the same lines for the same reason such as the power steering, brake assistance, and even the cabin heater hot water supply from the engine. No engine no hot water pumped to the heater.

John.

If the electric Battery went wrong then the whole car will stop functioning? No power steering, brake...

Britprius · June 21, 2020

2 minutes ago, aeroelastic said:

If the electric battery went wrong then the whole car will stop functioning? No power steering, brake...

You will loose power steering, but still have steering control. The brake system has an emergency backup capacitor supply, but this is very limited. The mechanical "hydraulic" brakes will still work but without power assistance.
This is no different to a normal car where if you loose the engine you will have no power steering, and only a limited number of brake operations before the vacuum assist is depleted, and no longer works.

John.

Herbie · June 21, 2020

1 hour ago, aeroelastic said:

If the electric battery went wrong then the whole car will stop functioning? No power steering, brake

Everything John says above is accurate but for a moving car.

If the traction Battery were to go flat due to lack of use or something else you wouldn't even be able to start the car. The 12v Battery boots the computers to get the hybrid system up and running and the hybrid system then energises MG1 which spins the engine up to about 1,000rpm before the system then applies fuel and a spark to fire it. Also, if the traction Battery was ever flat, then at 288V it's not something the RAC, AA or whoever could deal with; you'd need to get the dealer out or someone else with the necessary gear and knowledge to do it.

Oh, and if you run out of petrol then the most you'll get on Battery alone is about a couple of miles. It needs 12v Battery, HV traction Battery and petrol engine to be a functional car.

Britprius · June 21, 2020

As Herbie above says with the hybrids having at leased two batteries "some such as the GS450H with active suspension have three".
There is some confusion on what Battery powers what.
The 12 volt Battery generally powers the computer systems and normal 12 volt systems such as lighting, heater fans, and windows. The high voltage Battery "voltage varies depending on vehicle type" is use as a traction Battery, a starter Battery, and also used to run the power steering via a voltage converter to 40 volts or another converter up to around 500 volts 3 phase variable frequency AC for the aircon. It is also used to charge the 12 volt Battery via another voltage converter.

Running out of fuel, and continuing to drive till the high voltage Battery is depleted will put you in a position where the car will not start, and require recovery to the dealer to charge it. No amount of 12 volt jump starting will help because the car does not have a 12 volt starter motor.
If you run out of fuel, and stop reasonably quickly you will need to put around 3 gallons or 14ltrs of fuel in the car before the computer recognises that fuel has been added, and will start.

John.

aeroelastic · June 21, 2020

7 hours ago, Britprius said:

Thanks both for the replies, great insight into how a hybrid functions. Learned a great deal. Wouldn’t want to run the car dry on petrol at all...just something different from the usual engines I am used to. It’s for my wife but it’s a very good car. We used to have the rx300, and now this hybrid.