Alternator and AC woes

[Wonko]

Scratching my head trying to figure out why my AC failed and then a few miles later the alternator. This is on my 2006 V8.

The other day (hot day) I drove my car for about 60 miles, parked for about an hour then got back in to do the return trip. No AC. Blowing hot both sides. Sigh. I figure I'll get home and look at it there.

Not far from home all hell breaks loose. I get a message on the dash "EL Over current. Stop safely". Everything stops working. No power windows, no ABS, ESP, power brakes. Every single module starts giving an error message on the dash, it seems. Worse, there's a nasty burning plastic smell in the cabin.

I stop asap and have a look. Doesn't smell in the engine bay. Nothing to see. I limp home on small roads. Only one gear available to me - the trans is in limp. Had to hold the door open to get some air in the car.

At home, I disconnect the positive feed from the alternator, charge the battery and clear all the fault codes with Vida. All faulting modules seem to go back to working OK except the AC and the CCM. I get the message "Power system. Urgent service" or similar. Vida fault code says that the CCM can't communicate with the alternator. Car drives fine.

I'm resigned to the fact that I'm going to need a new alternator but I can't figure out why the AC isn't working. Or why that failed first then the alternator failed. The serpentine looks fine. No fault codes (other than air quality sensor which has always been there). The compressor is showing coherent duty cycles in Vida when AC switch is toggled and the pressure is around 1000 kPa which seems normal. The lines didn't seem to get cold though.

I hope that burning smell was coming from the alternator and not wiring inside the car...

I'm also hoping that the AC is not blowing cold because of the power system error message, but it doesn't seem likely.

Anyone have any ideas?

Thanks!

[SwissXC90]

Make sure you find the source, because next step could be this:

[Wonko]

Good. Then the problem would be solved.

[Tannaton]

I think the alternator is a common issue on the V8, more specifically the voltage regulator. I say that from memory of reading articles on here, it's also a tricky job to do unfortunately.

I would start there... as with most messages, get the codes read, which you have, and it points to the alternator.

If you search this forum another member, DaveSideways I think, posted some picks of what's involved to get at the alternator.

[Wonko]

Yes, I have also read that. And also Volvo have changed the design of the air duct to it, so it looks like a known weak point. Given where it is, I'm not surprised. Heat must be an aggravating factor. I'm not looking forward to changing it (I saw those posts about the extracting it).

Vida says it can't communicate with the alternator so it's either that or the LIN network somewhere inside the car. I won't know until I get a new alternator in.

Are there any good sources for OE parts? Volvo want about £600 for the part only.

[cheshired5]

Originally Posted by Wonko

Vida says it can't communicate with the alternator so it's either that or the LIN network somewhere inside the car. I won't know until I get a new alternator in.

Not necessarily.
If you have an AQS fault listed too, unplug the sensor as it may be disrupting the LINbus signals.

[Moose Test]

Originally Posted by Wonko

The serpentine looks fine. No fault codes (other than air quality sensor which has always been there).

The compressor is showing coherent duty cycles in Vida when AC switch is toggled

the pressure is around 1000 kPa which seems normal.

The lines didn't seem to get cold though.

Thanks!

If all that is so, it would suggest to me that it is possible that you have no refrigerant in the system and that the pressure switch is giving an incorrect reading (stuck, wiring fault etc.), which enables the compressor to keep cycling whilst empty.

When you were monitoring the pressure in Vida, did you see any major fluctuations as the compressor cycled? Can you read the return line and/or cooling coil temperature (I *think* I have seen this sensor data in VIDA for at least one Volvo I've owned but can't remember which model) to check the lines aren't cooling?

[Wonko]

Thanks, both.

Originally Posted by oragex

Could it be a blown CCM thermistor ? The power steering is working fine ?

I don't think so because the temperature readings are coherent. Power steering is fine.

Originally Posted by Moose Test

If all that is so, it would suggest to me that it is possible that you have no refrigerant in the system and that the pressure switch is giving an incorrect reading (stuck, wiring fault etc.), which enables the compressor to keep cycling whilst empty.

When you were monitoring the pressure in Vida, did you see any major fluctuations as the compressor cycled? Can you read the return line and/or cooling coil temperature (I *think* I have seen this sensor data in VIDA for at least one Volvo I've owned but can't remember which model) to check the lines aren't cooling?

My first thought was that I had managed to get a hole in the condenser then the alternator thing happened just afterwards which makes me suspect it's linked but it could just be a nasty coincidence. Exceedingly hot day might have caused both to fail in a short period?

The measured pressure varies a little, depending on duty cycle, which makes me think that the pressure sensor is giving coherent values.

I didn't see that additional data in the available Vida readings for the AC, but I will have another look.

I'm going to replace the alternator first and see what happens. Anyone have a source for discounted OE parts?

[Harley Dave]

Caffyns Volvo dealer sells on eBay

Cheers

Dave

[Moose Test]

Originally Posted by Wonko

I didn't see that additional data in the available Vida readings for the AC, but I will have another look.

It may be more simple than that. Out of curiosity I just tried detecting the temperature of the refrigerant by hand. The low pressure return side is the larger black metal pipe in centre of the attached picture (servo LHS, heater matrix supply/return RHS). The smaller diameter pipe below it is the high pressure feed.

I turned my aircon to full (ie. cabin temperature to min) and within 30 seconds of starting the engine the low pressure line (larger diameter) was unmistakably very cold to the touch. It was also quickly covered in a layer of condensation.

On that basis I think it's very easy to know whether the system is pressurising correctly or not.