S60 D5 weak heating

[tom570]

I have S60 D5 93kW from 2006 and already some time the heating is very weak. As the motor sometimes never achieved the proper working temperature and the hose going to the front cooler was warm almost since starting the car my first choice was the thermostat. Indeed the thermostat was faulty and now the cooler works properly and the engine heats up quickly. However the cabin heating didn't improve. Now when I touch the two heater hoses going into the car (with heating on max and fans high), one is very hot and the second is mildly warm. This leads me to belief that the heater core is clogged and I should go ahead and replace it. Do you think this logic is correct? If the problem would be with flaps or thermistor I presume both hoses would be very hot, right? Thank you very much for any ideas!

[4x4]

Both heater pipes should be hot, maybe you have an airlock

[stuart bowes]

replacement is not an easy job especially if you're left hand drive (?) if it turns out to be not just an airlock try flushing it through in both directions first that'll give you an indication

careful not to break the clips when disconnecting pipes they might be a bit brittle depending on age

[tom570]

Thanks a lot for reaction. Yes, my car is left hand drive. I don't think I have airlock, the system was drained during thermostat replacement and it is still the same. I decided to go for the heater core flush. I drained the coolant and now I am trying to disconnect the pipes as you mentioned The picture of them is attached.

I am trying to push the clips gently against each other while trying to disconnect the hose, but nothing happens. Should I use bigger force or is there some trick? Please help.

[4x4]

This should help... Click

[jnmonaghan]

Hi
I'm not sure how to put on links, however, if u look at utube videos by - peppermint - and select this one - volvo S60 heater core hose disconnect 2001-
-2004 -- this will show u how to disconnect the 2 heater hoses

Jude

[tom570]

Thanks guys, it worked. Yes, Peppermint videos are great. My hoses have different clips (see picture), that's why I was unsure. However brute force worked and the clips survived Now I have to buy some hose with proper size. The tubes have around 18 milimeters, so I guess 3/4" hose will be the one

[tom570]

So I flushed the heater core with tap water in both directions. It seems to flow just fine. I recorded that on video below. Then I did a flush with 5% citric acid and with occasional pumping I left it to soak for 2 days. Not much of a dirt was flooded out of the heater core (attached picture). So I put all back and tested the heating. Nothing changed, the heating is still weak. The motor heats up nicely to 90 degrees then the thermostat is opened and the cooler warms up nicely, so I believe the pump is ok. As to the pipes to heater core, when the fans are off both pipes are hot. When the fans are on max, the outgoing pipe cools down. It still looks like low flow rate, but if the problem is not in the heater core, how to easily troubleshoot it Would you please have some inspiration how to continue? Thank you!

+ YouTube Video

[DieselDoNicely]

Originally Posted by tom570

I have S60 D5 93kW from 2006 and already some time the heating is very weak. As the motor sometimes never achieved the proper working temperature and the hose going to the front cooler was warm almost since starting the car my first choice was the thermostat. Indeed the thermostat was faulty and now the cooler works properly and the engine heats up quickly. However the cabin heating didn't improve. Now when I touch the two heater hoses going into the car (with heating on max and fans high), one is very hot and the second is mildly warm. This leads me to belief that the heater core is clogged and I should go ahead and replace it. Do you think this logic is correct? If the problem would be with flaps or thermistor I presume both hoses would be very hot, right? Thank you very much for any ideas!

My 2005 V70 goes cold on runs. I have to switch the engine off and on again for it to start working. Could be a fail on yours.

[stuart bowes]

Not to overstate the obvious but the heater matrix is by very definition a way of taking heat from the water and distributing it into the air so yes, to some degree hot water will go in and slightly cooler water will come back out afterwards, I think you already know that.. the question is *how* cool is that other pipe.. one man's too hot to touch is another man's quite warm

Anyway you've proven water is flowing through fine, so hot water must be getting in there surely

Personally my next step would be to try a recalibration on the Hvac, or checking the thermistor as you already mentioned (depending which type you have), do you have VIDA or know anyone that does