XC70 climate control wierdness

[jwindwood]

Guys

I know climate issues have been covered many times but although I have read previous threads I can't find any symptoms like mine. I will describe....

This is a 2002 V70XC (Or XC70) that I have only owned for a week. I have however owned a V70 of a similar year previously, so I do know how it's supposed to work.

When I took delivery, the aircon was lukewarm. I got a local engineer to do a full diagnostic, regas and test. The system holds gas fine. We went away for a couple of days and first noticed that the aircon seemed to be very cold (Good!)
However, when the outside temperature dropped, we felt the need for some heat. Turned the heat knobs up gradually but it had no effect-still very cold. Eventually, after much experimentation, I turned the heat up full and the aircon off briefly, then back on-we then got heat!

Anyway, it remained cool so we didn't alter the settings again until today, when it became very warm outside. Turned the heat dials to full cold and noticed that the aircon is now barely cooling. After further investigation, it transpires that the aircon is still cooling but only out of the passenger air vents!

I was initially thinking that the climate control pack was faulty, but now I'm not so sure and I would be grateful for any advice. I'm a competent DIY mechanic so will try out anything suggested.

Many thanks.

John

[Missing Lincs]

Originally Posted by jwindwood

However, when the outside temperature dropped, we felt the need for some heat. Turned the heat knobs up gradually but it had no effect-still very cold. Eventually, after much experimentation, I turned the heat up full and the aircon off briefly, then back on-we then got heat!

Hello John.

I'm assuming from what you've said that you have the system with full climate control, in which case I'd suggest that the above is a symptom of a faulty thermistor in the CCM (Climate Control Module). If it is, the sensor can be changed, either replace the actual thermistor with a new one or the thermistor PCB from another known working CCM. Swapping out the complete CCM is complicated as it needs to be matched to the car and have exactly the same accessory configuration.

[stuart bowes]

could it be something as silly as dust in the hole? (hoover or brush it out)

if not, can it be 'repaired' in the same way as MAF sensor, i.e. a careful dose of contact cleaner

[Missing Lincs]

Originally Posted by stuart bowes

could it be something as silly as dust in the hole? (hoover or brush it out)

Dust will slow down the response of the the thermistor but it will still work. Gentle cleaning is a definite bonus but very, very gentle, the thermistor is a glass bead type with very fine leads, the body itself is about 1mm. The other possible is for the fan behind the thermistor to fail, again it will affect the response but it will still work.

Originally Posted by stuart bowes

if not, can it be 'repaired' in the same way as MAF sensor, i.e. a careful dose of contact cleaner

I'm afraid not. All the ones I've seen that have failed are either broken wires or the glass bead fractures.

[jwindwood]

Originally Posted by Missing Lincs

Hello John.

I'm assuming from what you've said that you have the system with full climate control, in which case I'd suggest that the above is a symptom of a faulty thermistor in the CCM (Climate Control Module). If it is, the sensor can be changed, either replace the actual thermistor with a new one or the thermistor PCB from another known working CCM. Swapping out the complete CCM is complicated as it needs to be matched to the car and have exactly the same accessory configuration.

That's great thanks-I was thinking thermistor from what I have read elsewhere. Do you by any chance know if these are the right ones?

https://www.ebay.co.uk/itm/172167726230

[Missing Lincs]

There's a good thread here click

Please check but I think this is the part Thermistor @ RS

[jwindwood]

That's great. Is it easy enough to remove and disassemble the climate panel? Can't find a guide.
Thanks.

[Missing Lincs]

If you've never done one before you need to be brave, taking the panel out is the hardest part if you've never done one before. There are some good guides on Youtube, V70 is same inside as XC70.

The main thing to remember is to disconnect the battery before disconnecting the Climate Controls. If you don't it will generate an SRS error which needs Vida or another suitable tool to reset.

The Climate Panel is clipped to the bottom the radio and especially if it's never been removed before it needs a strong pull to remove, as I say, have a look on Youtube for the technique.

Otherwise, dismantling isn't difficult. Soldering the sensor requires patience and a very small soldering iron. It might be easier to swap out the sensor in it's mount from a working second-hand CCM. Still needs soldering but the wires are larger and not quite so delicate.

If you want to try changing the actual thermistor I have a couple of spares, RS sell them in 5s and I've just done the one in my XC90.

[stuart bowes]

don't drop your torx-head bolts down into the center console when removing them.. you don't want the extra agro of finding them

just as you remove them get your fingers in there and hold on to them carefully

[Missing Lincs]

Here's one video from Youtube click

Not sure about using a screwdriver for leverage, I'd use something softer like a trim removal tool but the idea is there. Also, as I said, if the panel hasn't been out before it can be tight.