Heater Problems in 2006 XC90 D5 Auto 185BHP

Hurling · Post by **Hurling** » 02 Mar 2018, 07:09

Hello,

I have a 2006 XC90 D5 RHD and it has developed an issue with the heater, at best the heating is luke warm and at worst it is freezing cold. The problem is worse when the car is idling as there is no heat at all unless I rev the engine to about 2K.

I have plugged VIDA into the system and there are no DTCs other than a faulty glow plug on cylinder 5, I ran through a calibration of the CCM and it has made no difference. The thermostat seems to be OK as the car reaches temperature quite quickly with the temp gauge in the middle after about 10 minutes driving.

If I run the fan on a very low setting I do get a small amount of heat from the heater but if I increase the fan the air just cools until it is cold, while checking this I checked the incoming hose and it is very hot as expected but with the fan on high the return hose is quite cool.

I am thinking that the heater matrix is probably faulty but if anyone has anything else I can check I would be grateful.

I have replaced the heater core in my previous V70 classic and I have found guides for replacing the heater core in an XC90 without removing the dash but these have all been for LHD versions has anybody seen a guide for a RHD version?

Many thanks

Hurling

Post by **oragex** » 02 Mar 2018, 08:11

Hi and welcome

The thermostats don't last more than 10 years, here's how to quickly test them as they fail in open position preventing the coolant to get hot enough.

It seems the heater core gets very little flow or the coolant temp is not hot enough. Have you read the coolant temperature in VIDA once the engine is fully warmed up? It should be around 85C at idle.

I have read of two XC90 owners who had a similar issue and fixed it after replacing the heater core. Most probably - in my opinion - the heater core gets clogged if previous owners put some wrong coolant (the orange GM coolant is infamous for clogging see this video

Adding tap water is also a bad idea, only use demineralized or distilled water. If it turns out the heater core is clogged, I'd also try to replace the thermostat and see if the coolant passages are nice and clean. Here's someone who fixed an XC90 clogged core without removing it (remember to flush the product with a water hose after finishing)

Here's how to undo those hoses

As for the core replacement, I think it should be the same or easier on the RHD versions, just see on which side the two metal pipes go into the core. While the core is out, watch how the flaps (front an rear) inside are moving make sure they work properly.

Hurling · Post by **Hurling** » 02 Mar 2018, 08:57

Hi Oragex,

Many thanks for the reply, i will check the coolant temp in VIDA (as soon as I find where, still getting to know it), the engine seems to warm up as fast as I would expect and the temp gauge sits in the middle.

I should mention that the car has 126K Miles on the clock and i only bought it a while ago, love the car but I am wondering if I have bought a lot of cost after reading the forums...

Many thanks

Hurling

Hurling · Post by **Hurling** » 06 Mar 2018, 06:11

Hi,

I have had my local mechanic look and he has diagnosed a faulty thermostat, the temp gauge is showing correct but he said it is stuck open.

Even the thermostat is damned expensive...I will let you know if it cures the problem.

Regards

Hurling

Post by **oragex** » 06 Mar 2018, 07:05

It is necessary to replace the thermostat on a 2006, it will also help the engine run at a better temperature. While there, ask the mechanic to look for any gunk/sludge/calcium inside the housing, will get an idea if the previous owner used the wrong coolant or tap water.

Hurling · Post by **Hurling** » 06 Mar 2018, 07:39

Hi,

Thanks, I will probably ask him to do a flush and replacement of the coolant while he has it open, for the sake of a few extra £s on the bill it is probably worth it.

Post by **cn90** » 06 Mar 2018, 20:51

Search forum for the DIYs I wrote a while back...

1. Thermostat DIY, replacing only the tstat and the upper tstat cover. No need to touch the bottom tstat housing.

2. Heater Core for LHD...I also wrote it in forum. It can come out only on one side. Look around your car and you will find the answer. I suspect the HC comes out of the same side with the steering column.

MrTango · Post by **MrTango** » 09 Dec 2021, 05:35

Hurling, what did you find out in the end?

I have the exact same issue with the same model and mileage. Personally I think I will take a look at the Heater matric and flush this out in the first instance, then check the thermostat for sure.

Let us know

MrTango · Post by **MrTango** » 09 Dec 2021, 12:27

Hi there,

Does anyone know what the diameters are of the heater matrix in and outlet pipes please?

Thanks

MrTango · Post by **MrTango** » 13 Dec 2021, 08:09

Hi Guys,

So I flushed out the heater matrix over the weekend and it is sake to say I now have a heater that works.

I used a kitchen descaler product diluted in hot water and left for 90mins. I then flushed this out with plenty of water and then alternated between water and air to make sure that all of the old coolant and gunk was removed,

A couple of things to bear in mind, my XC90 has a strut brace fitted. it made it a much easier task to remove the brace and then flush the matrix, also, the pipes are 5/8" or 16mm. I used a heat gun on the end of the hoses to aid pressing home the hoses.

Thanks for this post guys, a big help!