V40: AC is going crazy

[AlexVolvo]

Hello fellas,
I have rather strange problem with the AC on my V40, 1.9D, 95hp, D4192T2
I cannot find similar thing anywhere.
Basically, it seams to me that the AC button looses power and both lights(green and amber) turns off. The REC and the heating rear widows are working just fine. This happens on irregular intervals. Sometimes when I'm driving 15 min or right after I start the engine. Then I put the car to rest for a night and in the morning it's OK.
What is more strange, when I turn on blower control knob (1-5 and AUTO) , the compressor is automatically started with the front (radiator) fan. After the fan goes off the compressor goes off too. It goes like cycle, that's why I keep the blower control at zero, to bypass the compressor.
By the way I used diagnosis (Delphi) and it's shows me that the AC button is always ON, trying to press it does not change this state.
Any suggestions ?

[pierremcalpine]

Originally Posted by AlexVolvo

Hello fellas,
I have rather strange problem with the AC on my V40, 1.9D, 95hp, D4192T2
I cannot find similar thing anywhere.
Basically, it seams to me that the AC button looses power and both lights(green and amber) turns off. The REC and the heating rear widows are working just fine. This happens on irregular intervals. Sometimes when I'm driving 15 min or right after I start the engine. Then I put the car to rest for a night and in the morning it's OK.
What is more strange, when I turn on blower control knob (1-5 and AUTO) , the compressor is automatically started with the front (radiator) fan. After the fan goes off the compressor goes off too. It goes like cycle, that's why I keep the blower control at zero, to bypass the compressor.
By the way I used diagnosis (Delphi) and it's shows me that the AC button is always ON, trying to press it does not change this state.
Any suggestions ?

For sure this is your ccm failing, not the Ac itself. I would try first spinning each of the dials on the ccm back and forth quickly about 20x each. You may get lucky and have this clean up some of the corrosion on the potentiometers in the ccm. If that fails Normally I would suggest thinking about replacing each of the pots (easy enough job if you can pick up soldering skills) but in your case I would suggest just heading to the wreckyard for a compatible ccm. I think your is shot.

[Jms153]

If I remember rightly when I had my v40 sport the blower fan had to on for AC to work
I prob thot the same as you at the time
My new v40 does exactly the same, switch off fan AC switches off

[pierremcalpine]

Originally Posted by Jms153

If I remember rightly when I had my v40 sport the blower fan had to on for AC to work
I prob thot the same as you at the time
My new v40 does exactly the same, switch off fan AC switches off

This is correct, OP - can you confirm that ac button stays on (either amber or green) when setting is anything but "0". It should turn amber (I think) when fan is at "0" setting.

I also re-read your original post, you should note that compressor turning on and off periodically is normal behavior. As for the AC fan, it should be on when compressor comes on (at least) and is sometimes on more than that to cool down engine.

I do not think that the AC button should ever turn off altogether though...at least not on mine. Always either amber or green.

[AlexVolvo]

I also think that the AC button shouldn't be off completely. But what bothers me that the diagnostic tool says it's in ON state. That makes me think there's a short-circuit. I'll open it these days and see if there is any corrosion or unsoldered components. I'm not sure but I don't think that inside the ECC there's potentiometer. Probably there are different resistors for each state of the knob. I already opened it not long ago to change the bulbs, cuz there was no light at all and I kept me driving insane in the dark hours of the day .
By the way, today there wasn't any problem at all what a crazy sh*t .
Someone told me that on some cars there is a blocking mechanism which doesn't allow you to turn on the AC, while outside temperature is bellow some negative limit.

[pierremcalpine]

For each dial, there is one pot which may be identical to the one in the ebay posting below. While there is no pot for the ac button itself there is a link between AC and fan speed i.e. if you turn fan speed to zero, then ac turns off. So what I was wondering was whether the pot on the fan speed had gone bezerk and had decided to randomly set its speed to zero thus turning off the ac.

Honestly though, it does sound like you have a possessed ccm. Ideally you would find a working ccm and switch if only to confirm that it solves issue.

I don't believe there is any sort of block. AC is helpful at any temp. I keep it on year round and it's always green...it also gets to -33degC here so I think I'd have noticed.

https://www.ebay.co.uk/itm/301725481...%3AMEBIDX%3AIT