2008 XC70 3.2

So after my issues with the thermostat (replaced, seems to have fixed) - was driving along and noticed some vapor coming in through the dash vents. Thought it might just be water vapor but then the code: P0483(68) - Engine coolant blower motor, rationality check - malfunction was thrown. Cleared it. Went on my way and the code is now back.

Possibly related - the other day I was driving along and stopped in traffic for a bit, the AC suddenly started to blow hot. I turned the car off and back on and everything went back to normal.

AC blows very cold, coolant temp seems correct - goes up to ~95 C, then back down and settles around 90-93 C. Coolant is full.

Any ideas? Has anyone had vapor coming out of the vents? Can't say I noticed much smell - maybe a slight 'dusty' smell but it was early morning so cooler than normal and the it rarely needs to blow hot air here (SoCal) so wondered if it was just dust in the vents.

Also do both fans come on together? I can see the top one is fine but need to get down and check out the smaller bottom one. Should both be on when up to temp and not moving or AC on?

Thanks!

 

the vapors could be condensation or a leaky heater core/ heater hose o-rings. I'd start by making sure the evaporator drain holes are clear so no residual water stays up by the evaporator. Next is the possibility you have a heater core issue. If you get a slightly "sweet" smell on initial start up (say the first 2-3 minutes) then you should feel for any wetness around foot wells near the center console and consider opening up the covers to see if you can see any signs of leaking around the heater core. Monitor your coolant reservoir to make sure you are not consuming any coolant (if not, its probably condensation). Last suggestion is to replace your cabin air filter and check for any debris (including mice nests etc)

 

Thanks for this.

Do you mind telling me where the evaporator drains roughly are?

And are the heater cores somewhere obvious behind the centre console?

I will monitor for smells etc. Am I right in thinking if I blast the heat it will exacerbate the issue for diagnosis?

thanks

 

Not sure about your model - My experience is with the 850s and S40s. Try searching Youtube for a video on replacing the heater core on and XC or V70 for some clues. As to blasting the heat, Volvos always run coolant through the heater core - when you turn on the heat, the HVAC opens a door that allows your cabin air to flow through the heater core and the ECC then adjusts the fan speed as needed. That won't make the leak speed up but may give you a stronger smell.

 

That vapor can be because the freon is too cold - like the vapor/smoke you see in your feezer when you open the door.

Ac stopped blowing cold - maybe because it was too cold. (as you mentioned) What is is temp being reported by the evap temp sensor? versus the actual temp coming out of the vents? I (my shop) have replaced a few of those, don't rememeber why. Too large a clutch gap is a common problem on most other Volvos with the 5 cylinder engines. I would imagine that's a possibility with the 6 cyl clutch also - but more difficult to measure ( you need a special kind of feeler gauge set)

Dusty smell is usually the dirty sock smell from water in the evaporator getting moldy. The default with most volvos is the afterblow function is turned on. That is about 50 minutes after the car is turned off, the heater fan comes on for ~7 minutes to dry the evaporator off and hopefully avoid the stink sock smell.

 

Thanks both - I will do some investigating this evening.

Any idea about the coolant blower motor code being stored? Seems like the fans work as expected (at least in terms of coolant temp and I can see the larger one spinning).

 

If the engine gets too hot - the compressor will shut off also. (due to a fan not working, or broken thermostat for example) Did you get that code from VIDA? If so click on the code for this diagnostic info. A good scan tool can activate the fans for testing - as shown below also

 

Hmm interesting. I only have a basic bluetooth scan tool and phone app - am I correct in interpreting the above as a possible binding fan? Or failing fan? They both seem to work as expected - I can see them spinning and they change speed depending on the temp. They also keep the car at ~93 C in hot traffic which is roughly what I would expect. I don't want to replace them unnecessarily but equally don't want them failing on a long trip.

Further to the 'dusty smell' - I tried various combinations with the climate control. If I turn the temp to high and heat the cabin then the air is warm and has no detectable smell. If I turn it to cold then the nice cold air that comes in also has no detectable smell. If I set it to somewhere in the middle then I get the stale/dust smell. Would I be right in thinking that in this middle state the CC mixes the AC air with some ambient air (roughly 36 C)? So possibly this ambient air is the source of the smell/dust? Where does it come in?

Unfortunately didn't see any vapour when I was doing this testing so that's still a bit of a mystery.

 

did you test to see how cold the air is coming out of the vents. Not sure of the exact spec but I'd expect it to be 40F give or take a couple of degrees. As Hoonk noted, its possible for ACs to be overcharged which can lead to a shut down on really hot days (had this happen on my VW CC - turns out my car (a CPO) had too much freon and that was causing the AC to "freeze up" on really hot days.

 

Fresh outside air is always pumped through the vents by the fan unless you have recirculation on. (or the system turns it on automatically) Fresh air comes in, all goes through the cabin air filter, then the ac evaporator and some air, depending on the temp requested, goes though the left and right blend doors, through the heater core to warm the air up to the desired temp for each side.

 

So the AC went warm today again - this time I plugged my scan tool in and monitored - coolant temp climbed rapidly so I suspect fan isn't on and AC/coolant aren't being blown on. Again, cycling the engine fixed it - AC went cold and temp dropped.

EDIT: Forgot to mention AC only blows warm/engine gets hot when stopped at traffic. When moving AC goes cold again and temp drops a bit.

This combined with the above diagnostic code leads me to believe faulty fan and/or control module. Now to decide whether to try a $30 control module or just go for the full assembly.

 

Replaced the fan - lots of driving up large mountains all weekend and not a sniff of issues/overheating/AC going warm so think that's sorted - thanks all!

Also think I've solved the vapour issue. At certain points over weekend there was very wet steam/vapour coming out of vents. Today I pulled carpet back, pulled the drain pipe off of the evaporator drain and a quite alarming amount of water drained out. I removed the 90 degree piece and cleaned loads of gunk out of it and reattached - think that's hopefully it. I have left the carpet pulled back drying but might have to remove it (and check the rear too I think). One question is when I put the 90 degree piece back in it didn't seem to feed into anything external like a pipe? Just sort of pointed through a hole - is this normal or do I have to hunt around for a pipe to attach it to? Doesn't look like it but just wanted to be sure I'm not just redirecting the water under the floor or something...

Thanks @hoonk @mt6127 !