Thread: new car honeymoon is over ... air con just died

So I've had my L322 TDV8 for a couple of months now and beside 3 bing bing epesodes followed by car lowering and of course the steering column with a min of its own, it been well behaved until now..

Ok so I drive to work last friday and everything is per normal... went to drive to a different site at lunch time and aircon is blowing hot air.. checked all the belts and fuses behind the glovebox and everything looks fine..

took it to a friends workshop and got him to check the gas... plenty but he did notice the low and high pressure sides where very close in readings..

fired up the scan tool and found a Left hand air temperature sensor short that just comes back after you reset it...
I did notice that it you play around with the air con switch it shows as flicking on then off straight away even thought the clutch doesn't kick in

my mate doesn't think it's related and think its the tx valve is shot....so

Where the hell is the TX valve located and also the sensor...and any other ideas??

Thanks in advance
CJ

Q: What type of compressor is it? If you can see the shaft spinning all the time it is Variable Displacement Compressor VDC Clutchless Variable Displacement Compressor - YouTube - if not and it has a cut out clutch than it is an old style compressor which is far simpler to deal with.

As mentioned above, if the compressor is not running the high and low pressures will be equal - well nearly. Once again there is differences depending on compressor type. old style will be exactly equal with maybe a tiny difference caused by engine bay heat - with a VDC it will be close to equal but there will be a measurable difference as the compressor never turns off completely, most drop to 5% when they are 'off' some a little higher - this is because the need lubrication because the internals are always spinning and that comes from oil in the refrigerant gas.

You need to understand what you have, and understand what the diagnostic equipment is reporting. Clutch systems are very simple - VDC add a bit of complexity, the most common issue being with the PCV (pressure control valve) - this is the valve that controls the angle of the 'swashplate'. Dealers will replace the compressor where the majority of the time it just the PCV, I had one that was just full of crap - if you know what you're looking for they can be sourced for about $30.

Does your 'scan tool' report on live values? Does it have a reading for "compressor clutch"? or a percentage request? obviously the car will only have one of these, and if they are not being activated by the ECU then I would be sorting the reported fault as it will be why the ECU is not engaging the compressor - the ECU recognises it can't operate without all its sensors.

However if you have a percentage requested value (or something to this effect - means it is VDC) and it is going up this means that the ECU is asking for compressor action - replace the PCV as it is what controls this.

** guessing time ** Your comment about it flicks on then immediately off indicates to me that the ECU is not trying to engage the compressor. If it was, I would think the light would stay on. With this information, if you aren't able to verify the live requests - get that sensor sorted and make sure there is no faults in the HVAC ECU.