Air Con pressure too high

[Veloces_]

Good afternoon Ladies and Gents.

IS300h F Sport 63 plate. (Had since new)

I have read a previous post headlined, 'AIR CON FAULT'. My problem is very similar, and I went to the same places, Halfords, KwickFit. Can i just add very quickly say that both companies were fine. The chap at Halfords stopped as soon as he realised there was a problem with the pressure on the low pressure side being far to high. I was not charged for this service. He indicated that there was a problem and after a search in the obvious places could not find any leaks. That same day I booked in to KwickFit, explained what the problem was, and on arrival to their garage a young lad took the car and placed it on a large machine hooking the Low and High pressure lines up. He dumped the refridgerant and refilled. Once he realised there was a pressure problem, he dumped the refridgerant again. This time he place another attachment on, Minutes later he came to me and explained the pressure was too high on the low pressure line.

I explained that I had already informed his supervisor of this problem, to which he he replied, 'Well its part and parcel of the fault finding procedure we have to go through' He then explained that he was vaccumming the system and would take about 1 hour 20  mins.

On completion, he regassed the system. Again, its reading was far to high although he placed the correct amount of refridgerant in the system. At that point he spoke to me again and said sorry, there was nothing more he could do. There was No Charge for their services, although he had spent around 2 hours plus working on my car.

The next day I booked with a specialist. Due the the recent weather there was a very high demand and the earliest he would arrive at my home would be 20:30hrs that day. I had to leave the car with my oldest son. I had to pick the wife up from work at 20:00. Anyway, on returning home the specialist was already at my home, bonnet up on my car and pipes fitted. He was in contact with his boss on his mobile. He had already dumped and refilled the system and guess what? Yep, the pressure was too high. I had already explained this to his boss during the initial telephone conversation and I did ask him for a diagnostic. The guy who performed the refill actually looked lost in his thoughts. Speaking to him again he suggested that the compressor must be broke, and he could change it for £1.5k and the car would be taken away and garaged for the work.

Now I'm no AirCon specialist, but even i know that a diagnostic would have been the correct procedure. When i asked him if he had done one, he said, there was no need. The compressor is the problem. This coming from a guy who didnt even know how to turn the car on, and when my son did it for him, and got out out to stand next to him, he pointed at the engine and said, turn it on then. To my sons surprise he told him that it was on and the car was a Hybrid. Anyway. I paid £70 for nothing, I didn't find out anything I didn't already know. (Just to add this specialist company are listed on the trust sight)

Ok, I have simple mechanics and electrical knowledge but am about 20 years out of date. I sat for the next 2 days checking various sites. Hidden on one particular site was a video released in the US by an owner who has vast amounts of info on Hybid AirCon systems. During this time he indicated checking the electrical flow from the Pressure sensor on the High pressure line. First checking the continuity of the plug itself. There was no continuity after checking all three pins.(Apparently there should be) Then checking the input voltage on the plug itself. The readings were correct being 5v - 8v range

I guess what i am asking is, is he high pressure sensor linked to the compressor by any means and would the faulty sensor prevent it from starting. Plus why would the new refridgerant automatically overpressurise in each instant.

Thank you for taking all that time to read this.

Regards

Shaun

 

[steve2006]

Hi Shaun and welcome to the LOC.

I do hope that the correct oil was put into the system!
 

https://carspecmn.com/toyota-and-lexus-hybrid-air-conditioning-special-service-requirements-prius-rx400h-camry-hybrid-etc/

Poor air flow over the evaporator coils ( when did you last replace the pollen filter?) can cause it as can a faulty condenser fan ( is it kicking in and out?).

Either way given the additional complexities of hybrid AC ( electric compressor, special PAG oil) I would suggest finding a specialist in that field and if you suspect the wrong oil is now in there move quickly.

Just out of curiosity what symptoms LED you to the problem?

[Veloces_]

Thanks fdr that.

1. The Pollen filter is a few weeks old.

2. The refrigerant used was R134A as specified on the sticker in the engine bay.

3. The condensor fan, I truely believe is working as intended.

3. As for the Oil type I'm 99% sure this has never been tampered with or changed.

The symtoms you ask about are constant warm air being blown through the vents when AirCon is on and internal circulation applied (Auto kicks in anyway) When i adjust the setting to exterior venting things cool down.

Those are the symptoms which are current

[Herbie]

2 hours ago, steve2006 said:

Either way given the additional complexities of hybrid AC ( electric compressor, special PAG oil) I would suggest finding a specialist in that field

PAG oil is absolutely what you do not want in a hybrid A/C system as it's a low dielectric and conducts electricity. ND11 is the one to use as it doesn't conduct.

1 hour ago, Veloces_ said:

2. The refrigerant used was R134A as specified on the sticker in the engine bay.

That's fine, the refrigerant gas is the same for both conventional cars and hybrids.

1 hour ago, Veloces_ said:

3. As for the Oil type I'm 99% sure this has never been tampered with or changed.

The oil comes out with the gas when the system is purged so it has indeed been changed, even though you may not know it and, as mentioned above, as long as ND11 oil has been used you'll be alright. It's been shown that even as little as 1% contamination by PAG oil will damage the compressor motor windings and lead to insulation breakdown.

You could try reading the OBD codes to see if anything is flagged up.

[Veloces_]

Thank you for your input..

What I think I need to know more about is the High pressure sensor on the High Pressure line, which has no continuity.The mechanic I watched performing tests on the video, said, 'Continuity must be present' The reason I gather is that if there is continuity then there is a circuite. There is definately a minimum of 5v supply going into the Sensor. but there must be none received. I take it, that if the ciruit is closed then there will not be any signal to the compressor to run it. Or, have I got that wrong?

As for the OBD codes, I have found a meter on amazon whiich reads all codes including AC side.

Thans again.

 

[Herbie]

I only have a workshop manual for the RX450h, not the IS300h, but from looking at that there's just one pressure sensor in the system and quite a few pages of stuff to check. You really need the OBD codes to even work out a starting point and then go into more in-depth diagnostics from there.

Let us know what they are when you get your code reader and hopefully we can help further. Just hope that you don't get a P0AA6 code because that could be very expensive to fix.

[Notamech]

Here is the service manual if it helps http://zatonevkredit(blocked word)/repair_manuals/viewdoc_html/AWHuj7EURvZszzJrV4Yg/AWHuk8RrrzlLPWuuGLBM

As others here have already mentioned you should never service your ac outside of the Toyota network as familiarity with hybrid systems is not very high among local garages. Hybrid ac systems use electric compressors and not belt driven ones like most petrol and diesel cars. Hence the compressor oil needed is different (non conductive) and you cannot use regular PAG oil. 

Just fyi the oil is a very small quantity that goes in with the refrigerant its job is primarily to lubricate the compressor and rubber seals inside the system. The machines that kwikfit and Halfords use to suck out and regas the ac refrigerant use regular pag oil. If your system has been contaminated with this it's going to be an expensive repair i think as its presence can cause things to short in the compressor. 

As far as your problem of too much pressure on the low pressure side, it is indeed typically indicative of a faulty compressor but as you have rightly suggested it still warrants proper diagnosis to confirm the problem first. My advice is take it to lexus or toyota alternatively look for a hybrid specialist. 

[Veloces_]

Thank you all for the input.. I have Obtained an OBD Thinkcar 100. I purchased this item due to reviews on Youtube and other Media outlets. Having conducted an error search there were 0 errors to be read. I'm pretty sure that if the compressor was at fault there would definately be an arror code as this forms part of the vehicles electrical system. I am not 100% sure if the Pressure sensor would show an error as the voltage reading on the harness plug are all correct, reading at 5Vs, but, there is no continuity from the sensor whatsoever, where there should be. So in my minds thought, that means there is an elecrtrical input, but, not being recieved by the sensor. Damn, I'm in 2 minds.. Degas and change the sensor and start over, which would be a hell of a lot cheaper than taking the vehicle to the dealership.