2002 Volvo S60 Cabin heating not efficient, the hot air is

321lor · Post by **321lor** » 10 Feb 2013, 06:49

Looks like I am going to need some help from the knowledgeable board members with regards to my 2002 Volvo S60 cabin heating problem
The problem is that the hot air coming through all the vents in the car is barely warm. When idling, for example at a traffic light is gets almost cold. It is warmer at higher speeds but well below the normal hot air it used to be, so the car cabin is never warm.
The air is still cold even when switching to manual with the fan at full speed, so the interior temperature sensor is not involved.
The coolant level was fine and I flushed the heater core with plenty of water until the rinse came totally clean. The input coolant hose into the core is hot, the coolant out hose feels cooler, but I guess it is normal, so flow of coolant through the core seems fine.
The coolant temperature is right in the middle and the coolant feels hot, so the thermostat operates properly.
I also changed the coolant and did a flush since it was about time, but it made no difference whatsoever.
Some time ago, a small rattling noise from behind the dashboard started. It is not the usual cabin fan bearings going bad.
The airflow into the cabin also seems less powerful now.
Any suggestions you might have are much appreciated.

Post by **regent** » 18 Feb 2013, 11:10

Do you know how much coolant you drained and how much you filled? I am thinking of possible trapped air in the system restricting the coolant flow through the core.

coolant hose into the core is hot, the coolant out hose feels cooler

If the air going through the core isn't gaining any heat, then the normally flowing coolant should not be loosing any heat either (hot-in/hot-out). From what you're describing (hot-in/cold-out, it looks like you have insufficient flow of coolant that is caused by a restriction - air bubble, kinked hose (almost unlikely) or foreign matter lodged in the system.

If you really do have "hot-in/hot-out" coolant through the core but still cold air is coming out of it, then this may be due to incorrect operation of the air flap valves (air is not going through the core)

Post by **jblackburn** » 18 Feb 2013, 11:31

If you turn the heater controls to full hot/full cold and wait a few seconds, do you hear actuators in the dash moving? Or ever a clunk-clunk-clunk like the flap is stuck?

WarbirdPilot91 · Post by **WarbirdPilot91** » 08 Jan 2015, 18:07

jblackburn wrote:If you turn the heater controls to full hot/full cold and wait a few seconds, do you hear actuators in the dash moving? Or ever a clunk-clunk-clunk like the flap is stuck?

Not to bump an old thread, but my '01 S60 is having this EXACT problem, and exhibiting these symptoms. Also, if I turn the switch over to re-circulation from fresh-air (besides hearing clunking) I also notice that all the windows begin to fog up. What could be the issue? Thanks!

Post by **jblackburn** » 08 Jan 2015, 18:11

WarbirdPilot91 wrote:
jblackburn wrote:If you turn the heater controls to full hot/full cold and wait a few seconds, do you hear actuators in the dash moving? Or ever a clunk-clunk-clunk like the flap is stuck?
Not to bump an old thread, but my '01 S60 is having this EXACT problem, and exhibiting these symptoms. Also, if I turn the switch over to re-circulation from fresh-air (besides hearing clunking) I also notice that all the windows begin to fog up. What could be the issue? Thanks!

Windows fogging up on recirculate will happen in any car. You need to use fresh, dry air on heat rather than recirculating moisture back through it.

If you hear a repeated tap-tap-tap noise instead of the actuators moving from one position to another, one of the flaps or motor arms is stuck. On the S70, they can be reached by removing the sides from the center stack; I would imagine the same is true for a S60, but do not know their exact location.

Post by **oragex** » 08 Jan 2015, 20:03

WarbirdPilot91 wrote:
jblackburn wrote:If you turn the heater controls to full hot/full cold and wait a few seconds, do you hear actuators in the dash moving? Or ever a clunk-clunk-clunk like the flap is stuck?
Not to bump an old thread, but my '01 S60 is having this EXACT problem, and exhibiting these symptoms. Also, if I turn the switch over to re-circulation from fresh-air (besides hearing clunking) I also notice that all the windows begin to fog up. What could be the issue? Thanks!

How is the coolant level in the reservoir? You may have a leak at the heater core. There may also be air inside the heater core making the cabin heating be inefficient.

WarbirdPilot91 · Post by **WarbirdPilot91** » 10 Jan 2015, 21:03

Hey again, gang.

So, to clarify, I CAN hear the actuators working, and feel the different options of airflow working. However, the actuators seem to take a while to move (like 3-5 secs.) The air that blows out, on highest heat setting, is luke-warm at best. I have all the other vents closed, except the 4 front dash ones.

The car is not overheating on the gauge (engine), but I will check the coolant level/condition tomorrow while it is slightly above arctic here in NY (LOL.)

My car is showing no other signs of a bad heater core, could some other component be at fault (sensor, t-stat?)

Post by **jblackburn** » 10 Jan 2015, 21:13

WarbirdPilot91 wrote:Hey again, gang.

So, to clarify, I CAN hear the actuators working, and feel the different options of airflow working. However, the actuators seem to take a while to move (like 3-5 secs.) The air that blows out, on highest heat setting, is luke-warm at best. I have all the other vents closed, except the 4 front dash ones.

The car is not overheating on the gauge (engine), but I will check the coolant level/condition tomorrow while it is slightly above arctic here in NY (LOL.)

My car is showing no other signs of a bad heater core, could some other component be at fault (sensor, t-stat?)

Slow to move sounds pretty normal - at least for the earlier models.

Have you ever replaced the engine thermostat on this car? Sounds like you may have a bad thermostat. At slow speeds with a bad thermostat, my S70 would warm up OK, but as soon as you hit higher speeds, the dash needle would drop to ~1/4 on the gauge. Heat was lukewarm at best.

Post by **oragex** » 10 Jan 2015, 22:00

The thermostat can be stuck open at this age, but if the large radiator hose after the thermostat is hot enough, then the cabin air should be blowing hot.

There might be air trapped inside the cabin heater. I'm having this problem and the system doesn't seem to properly burp it. I get hotter air when doing a left turn at speed, which means there's an air bubble inside the heater that's moving and doesn't let the coolant fully fill the heater.