XC90 V8 - Hot air problem ( or I should say no hot air! )

[Goldmember]

Hi guys,
Need some advice re the heating of my XC90 V8.
I only noticed the problem 2 weeks ago when the weather got colder. The problem really is it doesn’t blow warm air.
Facts are :
It runs fine, no coolant loss inside ( and outside as far as I can tell ) , not steaming up inside and no damp carpets.
Engine runs at perfect temperature ( 90 ) and temperature gauge sits perfectly in middle.
Controls work fine, goes ice cold when temperature controls are turned down to cold.
Ran VIDA and modules are working fine, no faults found. System calibrated.
Gave car to Voltech in Glasgow ( great garage btw ) who suspected it could be thermostat. So thermostat was changed, system was flushed ( lot of gunk came out apparently ), and new coolant in. They again checked with VIDA and calibrate the system.
Picked up the car and gave it a good run . I recon only 20% improvement . Air is luke warm when controls are turned up to max 26.
They are unsure what next but I cant go throwing major £ at the car and not solving the problem. They say it “might” be the water pump but no guarantee it would fix it and that would be a BIG bill.
Any recommendations people? Anything would be appreciated!
Thanks in advance,
Steve

[SwissXC90]

Does the vehicle reach normal engine operating temperature in normal time?
Measure in VIDA, not using the car's engine temperature gauge!
If so the thermostat is OK

The heating system for the cabin has only air dampers, no water valves.

If the cabin systems show no faults and normal electrical functions (use VIDA), including the interior air temperature, then electrically you have no faults.

If both of the above are true in can only be a blocked cabin heater core
If someone used some leakstop additive to the cooling system then likely the only solution is to keep on flushing until everything flows freely, then look for leaks and replace and leaking components (eg: cabin heater core).

[Essex boy]

Had the same problem with my D5, changed , thermostat, pump, recalibrated using vida (engine temp fine although diesels are slower at warming up than petrol).
Finally flushed the core with cleaner and its got better. ideally need to change the core, but its pain on right hand cars, unless you cut into some plastic!

[Goldmember]

Thanks SwissXC90 and Essex boy.
Regarding the temperature it was checked with VIDA . Definitely no leaks inside the cabin or engine bay etc.
I am torn as I spoke again at length to the technician at the garage who worked on my car re the thermostat and flush of the system and he reiterated it could be the water pump or the heating core , but there’s no guarantees with either that it will solve the problem and both big bills. So its a case of pick 1 and pay up
Unfortunately I can’t do anything myself as I’m not competent with a spanner never mind heating systems or engine. To me the heating core makes more sense .
Has anyone else got any ideas how I could distinguish which it could be or what else? I do trust the garage as they are experienced Volvo techs and have obviously worked on probably 100s of XC90s.
Another alternative is price up my local indi garage who I use for general servicing to carry out the lesser of these specialist jobs.. any idea which of these jobs is less Volvo specialised?
Sorry if these are daft questions!
Cheers,
Steve

[SwissXC90]

Sounds like they threw a thermostat at the car and then gave up....

If the water pump is faulty it would be overheating due to no coolant circulation

Refer to the VIDA guide for proper diagnosis. Maybe tonight I can get it for you and post it here

[Essex boy]

Easiest way to check if its the core
1: get engine unto temperature, feel the large hose at the top of the engine to ensure water is circulating and hose is hot

2: There are two rubber water pipes going into the bulkhead and heater core, they are over to the right just behind the engine near to the top

3: feel the pipes for the heat, right hand one is input, left is the outlet,

4: if you it feel hot on the right, then you have flow in, if cold or cooler on the left the core is likely blocked, hence no heat

5: if blocked get the garage to carry out a flush of the core, easy to do with the two pipes at the back

6: If the heat is working on both pipes and still nothing in the cabin, then it may need a VIDA re calibration of the flaps on the heater?

[owenfackrell]

Ive been going through similar things on my D5. I have changed my heater core, which is both easy and a hard as you do need to cut some plastic to get it out.
It has improved mine some what but i have yet to calibrate it with VIDA as i cant work out where it is on there, any pointers?
I have also replaced my water pump but that is because it started to leak from the shaft at 240k miles so it had a good run.

[oragex]

Originally Posted by Essex boy

2: There are two rubber water pipes going into the bulkhead and heater core, they are over to the right just behind the engine near to the top

3: feel the pipes for the heat, right hand one is input, left is the outlet,

Great idea. Try this test first with the cabin fan at off. Both hoses must be very hot (hard to keep the hand on) and have about the same temperature. Then turn the cabin blower close to max speed. One hose must now be quite easier to keep a hand on it.

Having had the thermostat replacement is a good thing, these start getting stuck slightly open after 8 years even when the temp gauge stays sharp at 12. Again, don't rely on the temp gauge being fixed at 12, the gauge can stay there anywhere from 80C to 105C. Here's how quickly verify an old thermostat https://www.youtube.com/watch?v=gQxQnuU22Ow

Having had gunk inside the system is most surely the culprit. This is not easily cleaned and using a garden hose is not only useless but also not a smart idea: a certain amount of tap water will remain inside the system and tap water=limestone deposits on smaller coolant passages.

Even replacing the heater core at this point, may not be enough. The best option at this point - and from my experience it definitely works - is a coolant 'flush and rinsing' treatment. This will not only clear the passages inside the heater core, but will also clean everything inside the engine cooling passages to ensure proper engine cooling in all parts of the engine. Also, in the future, use only a correct coolant brand mixed with only distilled water. Tap water should never be used inside the cooling system, be it only for a 'flush'. https://www.youtube.com/watch?v=69ymGTqHxRw

[Goldmember]

Originally Posted by SwissXC90

Sounds like they threw a thermostat at the car and then gave up....

If the water pump is faulty it would be overheating due to no coolant circulation

SwissXC90 - The garage said the water pump impellers may be worn rather than the punp failed therefore it’s not pushing the coolant round as much as it should, if that makes sense.

Essexboy - They did that at the beginning, and found that one of the pipes was significantly colder, so they flushed the system repetitively until they weren’t getting any more gunk out . Unfortunately this only gave like a 20% improvement in the vent temperature and we’re back to square 1.

Owenfackrell - Sorry it was another VOC member who had VIDA and I don’t remember what menu or where in VIDA it is

[SwissXC90]

Stills sounds like clogged heater core.

If the water wasn't circulating as good as it should then the engine would overheat easily