Alternator and AC woes

[Wonko]

Originally Posted by Moose Test

Those lines at the front are the flow and return to the condenser. They will never be cold if the system is working correctly - they are there to cool down the hot gas coming from the pump before it's fed into the evaporator in the car.

PS - I messed-up my high and low side in the previous post. The larger pipe is the LOW pressure return, it's the cold one.

Great to know. Thanks.

I've been researching a bit more. Seems like the voltage regulation circuit in the ECM is prone to blowing on the V8. Could mean a new ECM.

I've found a place in the USA that can "repair". Looks like they find a working unit and transfer the immobiliser / VIN info from your old unit. Not cheap though.

On the plus side, I might have found a Bosch alternator in the USA for £250 so that's better than what I was expecting to pay.

[Wonko]

Update on this:

I have replaced the alternator (that was NOT a fun job) and to my surprise that has resolved the electrical system problem and the fault code has now cleared. I was fairly convinced that I was going to have to repair the ECM.

However, the AC is still not working. I have no idea why. I unplugged the air quality sensor - no change.

Vida now shows

Vida shows the compressor status going from ~25% to ~78% (presumably duty cycle) when the AC button is off or on respectively. I can't detect any difference in engine load.

Now that the AQS is unplugged I get 2 faults codes:

CCM-0040 Air quality Sensor Internal fault

and also one that implies it's disconnected. I didn't note the fault code.

Odd that the internal fault is still showing even though I've disconnected it.

Pressure reading is ~750 kPa regardless of whether the compressor is on or off which I find odd. It does change very slightly. Since that's about 100 psi, then I assume it's the high-pressure side. I don't have my AC gauges with me so I can't check for gas, but 100 psi seems like a lot if there was a leak.

I'm at a loss now as to what to do to diagnose further.

Any ideas? Thanks.

[cheshired5]

Originally Posted by Wonko

Vida shows the compressor status going from ~25% to ~78% (presumably duty cycle) when the AC button is off or on respectively. I can't detect any difference in engine load.

View the ac relay status in Vida whilst physically looking at the ac compressor clutch operation.

Vida saying the ac relay is on yet you have no ac performance despite an engaging compressor clutch is different to no ac and no compressor clutch engagement.

You also need to confirm credible readings from the cabin and evaporator temperature sensors.
Perhaps even do a CCM calibration in Vida.

[Wonko]

Thanks for that.

Cabin temperature is coherent, evaporator temp started at 25 and is now at 35.

I can’t see a status in Vida for the AC relay, but I can hear it click on and off when inactivate it with the engine off. I need to physically locate it.

I don’t know how to see whether the compressor clutch activates or not. Can you give me a pointer?

I did a CCM calibration. Made no difference.

[cheshired5]

The clutch plate is the disc on the end of the compressor pulley.
When not engaged, the clutch is stationary whilst the main pulley still turns with the engine.
When engaged, the clutch plate is pulled in by an electromagnet and turns with the pulley.
The compressor then works to provide ac.

At this time of year, you should see the evaporator temperature reduce to around 6°C then the clutch will disengage, evaporator temperature will rise towards 10°C, the clutch engages, evaporator temp drops and the cycle continues ad infinitum.

[Wonko]

Chesired5, you've really helped me to get a handle on the problem. Thanks.

I managed to get a look at the compressor while my wife started and stopped the AC. Short video here:

https://1drv.ms/u/s!Ao8CBdf9s4C6jlijb06OAsjnfxNR

That doesn't look like normal behaviour to me. It's basically freewheeling and occasionally catches briefly.

Also, I spot that black goo around the pulley. I suspect that's melted clutch material. And I suspect it is this that I smelled when everything went to pot, rather than electrical burning.

So my theory now is that after a longish drive on a hot day (almost 40 degrees IIRC) I parked the car for an hour to heatsoak then straight back onto the motorway. I think the clutch got really hot and melted and the alternator also chose that moment to hari-kari from the extreme heat. I don't think one took out the other, but rather that the heat was the common factor causing failure of both.

Looks like I'm in for a compressor change. I hope it's not as much of a nightmare as the alternator replacement.

Anyway, thanks everyone for your help.

[IainG]

Hi

[QUOTE]Looks like I'm in for a compressor change. I hope it's not as much of a nightmare as the alternator replacement. /QUOTE]

Is it possible to just change over the clutch and pulleys rather than have to de and re gas the system?

Iain

[cheshired5]

You could change the pulley and clutch assembly without replacing the compressor but you'd be unlikely to be able to do it with the compressor in situ due to poor access.
By the time you've degassed and removed the compressor, bought the replacement components and pullers if you don't have them, a whole new compressor may not be too bad an alternative.

It also looks like the clutch plate is missing completely when comparing the parts diagram in Vida with the posted video.
I'm not familiar with what's normal on the V8 though.

[Wonko]

Right, I can get a new clutch assembly from Volvo for 280 quid, a whole compressor for 650 quid, or I can get a new OE Valeo compressor for 250 from Autodoc.

I'm going to buy the Valeo compressor and try to use the clutch from that and change in situ. I'm not convinced I'll be able to get the required access to get the clutch out, but I think it's worth a try. Worst case, I've already got the whole compressor if I need to go down that route.

I don't know any AC people near where I am, so I'd rather avoid having to find someone who will accept degassing and re-gassing later.

[Wonko]

For anyone looking for the alternator part number, it's:

BOSCH AL0821X

I got it from Rockauto and it's identical to the one that came out.