XC70: Electrical Climate Control Issue

[zapcity1]

Hi all, I have a problem with the climate control on my '09 XC70 D5.

When starting up, everything works as expected. The blowers push out hot air and the cabin gets up to temp (set at 21-23) in about 10 mins. All as expected.

When the cabin temp is reached, the vents on top of the dash start to pump out cold air (was hot). It appears that the cabin temp then reduces as it definately becomes colder. I can manually reduce the flow of cold air by turning the fan speed down to minimum and manually directing the air, but I still get a cold draft from the dash top vents enough to make it uncomfortabe.

I've run a VIDA diagnostic (I'm no expert in VIDA by the way!!) with the following result (see attachement): -

CEM-B10EA14 - Positive Temperature Coefficient heater - General Electrical Failures - short circuit to open or ground

I know my car has the PTC heater fitted (as confirmed by VIDA), but I thought this was used to supplement the car heating from cold, as it's effectively a high kW heating element. Therefore I can't understand why I'm getting the issue I am. I would have though that if the PTC heater is faulty I would get slow initial heating follwed by normal heating once the conventional system is up to temperature but this is not the case. Once my cabin is up to the set temp., then it starts to blow cold.

This PTC element is buried in the dash (item 29 on attached pic), but I don't know if the error code relates to this or the CEM itself. VIDA gives no instruction on replacing the PTC element either.

I've seen this issue on a couple of older threads on other forums, but not with any resolution.

I have the option to recalibrate the CC, but VIDA doesnt show this as being an issue.

Just wondering if anyone else has seen this issue, or can offer advice before I get the dealer involved. Thanks.

[Tatsfield]

More logically it would be the electric heater which is initially providing the heat from cold and when it achieves its working temperature, it turns itself off and leaves the engine coolant heat source to take over. As this is not happening, it could be that the fault is with the flow control system providing the flow of hot coolant through the heater matrix.

[tt82]

I get this sometimes as well.

It isn't stated in the manual but with my old 2001 V40 it stated that the dash air vents always take a feed from the outside. If you look in the owners manual, pg 129 it shows that when you manually choose the direction of air flow, if the dashboard air vents aren't selected, it states "Some air flows from the dashboard air vents." I believe this refers to the same airflow from outside that older models had. If you manually select the dashboard air vents, then the air coming out warms up.

My personal opinion, based on using the auto mode of climate control is that you get in the cold car and get warmer as it warms, generally by using the windscreen and dashboard air vents, possibly the floor vents as well. Once the car reaches the required temperature it moves the air from the dashboard air vents to the floor vents to maintain a comfortable temperature. This allows air drawn in from outside to pass through the dashboard vents. Depending on where these vents are directed, the draft makes you feel cold even though the car is maintaining a set temperature.

There is a warning in the manual about the B-Pillar vents and small children being sensitive to air flows or draughts. Perhaps you also are quite sensitive to them or you have the vents aimed differently because generally I can drive for up to 2 hours before getting this sensation.

[zapcity1]

Had a little play and discovered the following.

When the temp is set to the same each side (22 for info. outside temp. indicated at 12), the cold air was only coming from the drivers side vents. The passenger side had a very slight airflow as expected.

Cranking up the heat to 30 both side the air delivered got hot very quickly.

It seems that I can't stop the air coming from the vents (in auto mode) on the drivers side.

As each side is individually controlled, I'm wondering if there is an issue with the actuators on the drivers side.

I think these can be tested in VIDA, so will take a look tomorrow.

[Model flyer]

Try moving heat from lo to hi a couple of times and blower controls to their limits to re-calibrate as servos can get out of sequence. Also is your battery OK as low voltage can cause all sorts of gremlins and strange problems .

[zapcity1]

Originally Posted by Model flyer

Try moving heat from lo to hi a couple of times and blower controls to their limits to re-calibrate as servos can get out of sequence. Also is your battery OK as low voltage can cause all sorts of gremlins and strange problems .

Thanks for tip. Yes my battery voltage is lowish. I get the headlight failure warning flash up when starting, which I understand is due to the battery voltage. It doesn't affect starting etc, but I had planned to replace it at some point.

[zapcity1]

Well it seems like I've sorted this issue, so would like to close it off and document for those who may have a similar problem down the line.

I went through the summer without fixing it as a lack of heating wasn't an issue! Lived with it until Christmas, but then it seemed to get worse. Freezing cold air delivered from dashtop and windscreen vents only tempered by switching to 23 degree manual heat from dash vents.

As the cabin temperature sensor in the centre console is an easy change, I decided to do this first. Not sure it was the problem, but a 2nd hand part from eBay was only £10, so nothing to lose (FoMoCo part 6G9N-19C734-AB used on lots of Volvos, Fords and Land Rovers).

I had a small rattle/buzzing from the bottom of the centre console, so decided to fix this at the same time.

When changing the temp sensor, I noticed the original part had a rattle when shaken, which was not there on the replacement. Could this be my mystery noise?

Anyway, temp sensor changed and reassembled and the rattle has gone. Test of the CC and all is working as expected. CC now set at a sensible self-regulating 20 and very comfortable.

Original fault code also disapeared from VIDA: - CEM-B10EA14 - Positive Temperature Coefficient heater - General Electrical

Fantastic result!! Thanks to all that helped.

[Waynedance]

Thanks for coming back with the solution, wish everyone done that.

Glad you got it sorted.

[Angus251]

Originally Posted by zapcity1

Well it seems like I've sorted this issue, so would like to close it off and document for those who may have a similar problem down the line.

I went through the summer without fixing it as a lack of heating wasn't an issue! Lived with it until Christmas, but then it seemed to get worse. Freezing cold air delivered from dashtop and windscreen vents only tempered by switching to 23 degree manual heat from dash vents.

As the cabin temperature sensor in the centre console is an easy change, I decided to do this first. Not sure it was the problem, but a 2nd hand part from eBay was only £10, so nothing to lose (FoMoCo part 6G9N-19C734-AB used on lots of Volvos, Fords and Land Rovers).

I had a small rattle/buzzing from the bottom of the centre console, so decided to fix this at the same time.

When changing the temp sensor, I noticed the original part had a rattle when shaken, which was not there on the replacement. Could this be my mystery noise?

Anyway, temp sensor changed and reassembled and the rattle has gone. Test of the CC and all is working as expected. CC now set at a sensible self-regulating 20 and very comfortable.

Original fault code also disapeared from VIDA: - CEM-B10EA14 - Positive Temperature Coefficient heater - General Electrical

Fantastic result!! Thanks to all that helped.

Hi

Just found your post about electric heater issues
CEM-B10EA14 - Positive Temperature Coefficient heater - General Electrical

I wish to ask if you come across similar fault

B10EA13 - Positive Temperature Coefficient heater - General Electrical fault. OPEN CIRCUIT ??

I have stripped my s80, checked all wires and so on, all fuses ( unless I missed any ).
Got volts on main power connectors and so on.

All look perfect.

Would you be able to speculate ??

[Calum86]

Hi,

I have had the same fault codes and I believe symptoms, the drop below freezing seems to really trigger it. Was wondering if you could tell me the location of the sensor?

Thanks