2006 V70XC Only warm heat when heater on high.

Bluegrassxc70 · Post by **Bluegrassxc70** » 31 Dec 2017, 21:07

Hi all.

This is my first post so go easy:). I did search and those results guided the actions below.

I have a 2006 xc70 with 130k on it. I purchased it about 5mo ago. We are finally getting into seriously cold weather and I have noticed that the cabin is not heating up quickly.

I started to investigate and here is what I did/found after drinking the car at highway speeds for 20 min...

1. Measured temp at vents with fan on high and heat on high: 100F. Seems extremely low. (Cabin temp was probably 60f and outside temp was apx 20F). System was set to recirculating and no ac with blower to max.
2. Measured temp at thermostat and upper radiator hose: 175ish F
3. Measured temp at heater core inlet and outlet hoses with laser thermometer: 165f inlet and 130F outlet.
4. Removed glove box and other panels to verify function of various dampers and all seemed to move smoothly when actuated.
5. Removed inlet and outlet to heater core and ran tap water hose through outlet and verified that there was good flow out of inlet. All seemed good.
6. Forgot to mention... coolant level is between min and max.

So at this point I’m thinking that the heater core is partially blocked (I’m assuming that this is a tank style heater core) and therefore I’m not using the entire core, or the damper door that diverts flow across the heater core is not closing all the way and I’m getting only partial flow across the heater core.

Any thoughts, suggestions, or guidance?

Post by **abscate** » 01 Jan 2018, 05:25

Great first post, Welcome!

You've done just about everything I would suggest, let's see what kind of numbers come back on dash vent temps.

My 99 took my cabin up to 80F with outside temp of 0F after 5 minutes if driving so you are cold.

I would guess damper door seal failure over plugging of core, especially since you've been changing coolant every 2-3 years, right?

Bluegrassxc70 · Post by **Bluegrassxc70** » 01 Jan 2018, 06:22

Thanks for the response and the welcome.

Anyone have any suggestions on how to dig the root cause without pulling the dash!!

Also, I noticed that when I pulled the side panels to have a look at the blend door actuators etc, I could see what looked to be the bottom right corner of the Hester core. It was a ribbed plastic piece that was a goldish color (I’ll get pix next time). When I had the fan running with heat on full, the temp was pretty low (can’t remember exactly but 90-100). Then wen I turned the blower off it would rise to 130ish (again, my numbers could be off)

Is that indeed the end cap of the heater core? I would have expected it to be up to heater core inlet temp (165) when the fan was not blowing if it were operating properly.

Thanks again for the help.

Post by **oragex** » 01 Jan 2018, 08:34

Hello

Have you already replaced the thermostat? At 130k it's more than time for it. Here's how to verify if it got stuck open (even just partially)

The heater core can trap air inside

The heater core may also crack inside without leaking, causing poor heat transfer and poor cabin heating (there are other videos on Youtube on this subject)

Post by **abscate** » 01 Jan 2018, 08:35

If you have full flow on the heater core ( congrats on getting the hoses off, by the way, that isn’t easy) I think that rules out plugged core on the water side. You could pull the core and test the air side for plugging

It’s 3.2 hours to remove part 9171503, which is part number for my 2005 V70. Believe that fits all P2s

The video above shows removal without dash removal, which is much easier. Watch the whole video before trying, you don’t have to trim the plastic as the mechanic notes, if you unbolt the steering linkage and move it out of the way

Bluegrassxc70 · Post by **Bluegrassxc70** » 01 Jan 2018, 11:53

This site is awesome!

Thx for the video links!

My thermostat is working properly.

I thought about possible air in the system. I was going to simply jack up the drivers side to try to get the core at an angle and rev the engine in neutral to drive the water pump revs up.

The video showing core removal with out dash removal is great! Appreciate the guys effort to make a clear video. Looks very doable. That will be the last option but likely sooner than later:/. It will also let me see the damper doors articulating and verify that it’s proper.

Thx again for the help.

Bluegrassxc70 · Post by **Bluegrassxc70** » 01 Jan 2018, 12:51

Tried to get air out of the system... no improvement. More to come. But may be a few days....

Post by **RickHaleParker** » 01 Jan 2018, 13:00

When I suspect a heater core is blocked, the first thing it do is reverse the flow at the firewall. Sometimes a backflush is all it takes.

Bluegrassxc70 · Post by **Bluegrassxc70** » 01 Jan 2018, 13:12

Ya. I tried a backflush. I had what seemed like good flow.

I may try to pinch off the inlet with a pair of needle nose vicegrips with sections of hose on the ends, then take the outlet line off and start the car. Then let off the clamp I have on the inlet and see what kind of flow I actually have from the water pump through the core.

Post by **abscate** » 01 Jan 2018, 13:47

We have had really few plugged heater cores here. Maybe some guys in the trade can comment. If your coolant is clean, it’s something else.likewise, few reports of air locks. I think you have an air door or blend door/motor problem