XC70 Climate Control Temperature Sensor - Replace or Repair?

james166 · Post by **james166** » 16 Jul 2017, 21:01

I have a 2006 XC70 and the climate control module is not regulating the cabin inside temperature properly. I was told by my volvo dealer that the temperature sensor in the CCM is broken. So, I'm looking at a few options to fix this, including:
1) The dealer recommended having them replace the CCM at a cost of $1100.
2) I could remove the unit and send it to Xemodex for about $350 they will repair it.
3) I could buy a used CCM on ebay (about $50-100) and remove the (hopefully good) temperature sensor and put it in my unit. I'm not sure how feasible this is as I have never had one of these apart. Replacing the whole unit is not a good option as it would have to be programmed by the dealership.
Any advice on this would be appreciated.
Also, I'm not sure how to remove the CCM, so if anyone has instructions on that please let me know. I've seen some online videos but they all seem to be for older models. So far, I have removed the plate around the shifter and I can see two torx screws at the bottom that look like they are holding the center console in place. But the trim around the console does not seem removable so I'm not sure how to proceed.

Post by **jonesg** » 16 Jul 2017, 21:50

Dig a bit deeper on youtube, I've seen vids to remove that center section, had to do my handbrake and I was having the same problem trying to get the plastic bits off. I don't know for sure but you might want to see this.
I'd disconnect the battery.

DrDan · Post by **DrDan** » 26 Jul 2017, 03:58

Definitely disconnect the battery before you remove the ECC unit. The ECC is sort of a hub in the CAN-bus topology and the SRS is connected downstream of ECC. If you don't disconnect the battery you will get an SRS code which can only be reset by the dealer or, I suppose, using VIDA and DICE at home.

That said, the quoted cost for repair is insane. If it's really just the temperature sensor, it's not hard to fix. So for either the original poster or as reference for anybody who cares, here's how to open up and fix the ECC unit.

Removing the ECC is tough, the way the ECC, Radio and Carphone are mounted in the pre-facelift P26 is a real mess in my opinion (I don't know if the later ones are better). Don't be shocked if you break or bend the metal hooks holding the ECC. Once the unit has been removed, though, the repair is easy if you can do elementary soldering. Before you go remove the ECC from the car, check if the sensor is actually bad (read out temperature using VIDA or if you have RTI, I think interior temperature can be read on the debug screen which is activated by repeatedly pushing OK/Cancel when RTI is powered on. Check for plausibility). Also, check if all the lights on the ECC are working, this would be a good opportunity to change bad bulbs.

On the back of the unit there's a little fan which circulates air from the car's interior across the temperature sensor. Remove it (green connector and screw) and clean it, you'll probably find lots of dust inside.

: back of ECC; IMG_20170720_080454676_HDR.jpg (854.54 KiB) Viewed 16793 times

Then, turn the unit so you're looking on its top. Unlock the black tabs and remove the back cover. No need to mess with the knobs or the front plate at all.

: Tabs; DSC_5773_arws.JPG (4.58 MiB) Viewed 16793 times

Undo the four screws and carefully remove the PCB. To do this, you need to unhook the black plastic part holding the temperature sensor, just right to the top left screw.

: PCB; DSC_5771_arws.JPG (5.81 MiB) Viewed 16793 times

Turn around PCB, et voilà, the temperature sensor is the brown drop labelled TH1. You might find that yours has been damaged by somebody poking it with a sharp stick through the grille, trying to dust it off. Unsolder the cable at JW1, swap in replacement sensor or fix the connection as appropriate. Reassemble.

: temperature sensor; DSC_5770.JPG (4.92 MiB) Viewed 16793 times

Now, the sensor itself is a thermistor, i.e. a resistor with a marked dependency of resistance on temperature. If it's parameters were known, you could just replace the thermistor by a close match from an electronics store and cut the cost of the repair down to at most 5$. The thermistor's parameters can in principle be computed by means of the Steinhart-Hart equation https://en.wikipedia.org/wiki/Steinhart–Hart_equation given resistance readings at two different known temperatures, but at this point, I don't have a decent thermometer to measure temperature.

Good luck fixing the ECC!

On a related note, there's another temperature sensor in the climate condenser which you could check, it's easy to replace and cheap, but if it is bad, changing it will make a world of difference to climate control.

Post by **chrism** » 26 Jul 2017, 08:57

Have you tried sucking the dust out through the front slots with a good strong vacuum?

It seems I recall discussions about this in the past and somebody said there's some sort of tiny fan in the backside that pulls cabin air into the sensor - along with whatever particulates that happen to be floating in the cabin air (dust, cigarette smoke, bodily gasses, etc.) I believe that as I vacuumed a pretty good slug of dust out of mine a couple years ago.

DrDan · Post by **DrDan** » 27 Jul 2017, 06:10

True. You can see the fan in the first picture of my post above, it's the thing labelled W130. If the air flow to the sensor is obstructed, it will heat up and report a biased value. Verifying that the sensor is actually faulty should be the very first step into this.

Post by **JRL** » 27 Jul 2017, 09:35

Buy a used one from Erie Vovo that has a lifetime guarantee and be done with it.
www.erievovo.com
or
1 888 VOLVO-13

DrDan · Post by **DrDan** » 27 Jul 2017, 10:33

JRL wrote: ↑27 Jul 2017, 09:35 Buy a used one from Erie Vovo that has a lifetime guarantee and be done with it.

Are there software incompatibilities to be aware of? It would be great to know if my spare ECC from a 2000 (MY01?) car would fit into my MY02 car.

Post by **abscate** » 27 Jul 2017, 11:02

I think you just crossed the zone between P80 and P2 with that model jump.

DrDan · Post by **DrDan** » 27 Jul 2017, 12:46

I can't say for sure, if I recall correctly, the seller claimed that the donor car was built in 2000. According to Wikipedia, the P2 went on sale in 2000, so it might be correct. The ECC was sold in a bundle with an HU-601 which I really was after, so I never tried it in my car anyway.

Post by **SuperHerman** » 27 Jul 2017, 20:17

Compatibility really depends on what software is in the unit and in other units from what I understand. I did a like for like swap in my 2002 XC70.

Now if they look alike - maybe just swap the thermistor if it looks the same. Maybe will even have a marking on it.

When I looked at this issue years ago I recall seeing some having luck sourcing the thermistor. Do some digging and maybe you can find info.