Intermittent Heat - 2005 XC90 2.5T

[vcsuri]

Hello all,

Brand new heater problem just in time for winter! Every time I run the heater, it will blow hot air for 3 seconds and then ice cold air for another 3 seconds. When this happens, I can hear a mechanical noise of something maybe opening and closing, and the noises happen every 3 seconds with the change of air temperature. Issue happens no matter how long the car has been running. Looks like heated seats will be my best friend this winter!

Please let me know your suggestions, or my NJ winter won't be any fun to live through!

[RickHaleParker]

When was the last time #12 was cleaned out? Dirt and other debris gets sucked in through the vent on the climate control panel. There in a small fan in the sensor that pulls air through the sensor. If the air flow is restricted or the thermistor is dirty, the sensor will not read the temperature correctly.

Be careful the fine wires to the thermistor inside #12 are easily damaged. I suggest you remove the sensor, blow it out with your lungs and a straw then clean with MAF cleaner.

Click picture to zoom in.

[cn90]

In my 2005 XC90 2.5T...

The thermostat opens too soon...at 110K.

The heater core has reduced flow...at 115K.

New tstat and heater core later: car is nice and warm. I did the write-up DIYs in forum.

[vcsuri]

When was the last time #12 was cleaned out?

Thank you RickHaleParker for your reply. I cleaned this sensor and I have no luck. The problem is still happening. Do you have any other suggestions?

In addition, I now have an SRS-Airbag fault on my dash that has only appeared immediately after removing the radio/AC unit to reach this sensor.

Any suggestions on how to clear that message is greatly appreciated.

[wanderdüne]

Sounds like the blend door is opening and closing.
Does it happen/ make a difference when:
-the climate control is on auto or manual?
-is the hot/cold air happening at all vents?
-the re-circulation is on?
-on manual on just vent or on manual with just floor setting on?
-independently of where the temperature knob is set?


^^^just saw above post about SRS^^^
*Turn off all switches/ temp knobs etc.
unhook your battery for 5 minutes; the - then the +
Turn key to position II
Attach the +, then the - Battery cable
Allow all the modules to stop activating
Turn key off, then re-start; SRS *might* go away.

[vcsuri]

Thank you wanderdüne! Here is the answer to all scenarios.

Does it happen/ make a difference when:
-the climate control is on auto or manual?

It's on manual. However is also happens when the system is on auto too.

-is the hot/cold air happening at all vents?

Hot/Cold air happens on every single vent in the car.

-the re-circulation is on?

Re-circulation is always on. Happens with it off too.

-on manual on just vent or on manual with just floor setting on?

Manual is on the vents and on the windshield, not on the floor. However, it also happens when I activate the floor vents too.

-independently of where the temperature knob is set?

Happens only when the temperature knob is past the half-way point, so whenever heat is activated.

And in testing these, I just made a new discovery: if I set both knobs to 68ºF, and then move both 1 click at a time to the hottest setting, the noise stops and I have normal heat. Every time I turn one click, I can hear the same sound, however it's a quick sound of something moving and then it stops. However, when I turn from 68º all the way to full heat in one motion, then the noise returns and the hot/cold air returns too.

And about the SRS message, I just purchased a scanner that is able to read all modules, I'm hoping I'm able to clear that SRS message then. I'll update whether it worked or not. It had good reviews from Volvo owners and the device is a specifically built for Volvos. I have the Blue Scanner, which works great for scanning all modules on my Camry, but unfortunately doesn't support Volvo, despite supporting other European makes.

[vcsuri]

Just an update, I found this post from 2016 on this issue. Apparently Volvo issued a Technical Bulletin for this, and it's detailed on this post.

viewtopic.php?t=26401

Could anyone confirm if the calibration detailed in this technical bulletin solves the problem?

And what should I do, buy a VIDA device or simply take it to a Volvo specialist?

[wanderdüne]

You can get a copy of the software (VIDA) here to download: https://forums.swedespeed.com/showthrea ... nload-Link
You can buy a DiCE (hardware) clone online on ebay or amazon etc. Here is an example https://www.ebay.com/itm/VIDA-DICE-2014 ... Sw9XhdcGJD I am not recommending this one per se' just an example. If you buy one like this you do not use the CD ROM that comes with it, use only the tool in conjunction with the software download above. Throw the CD away.

I don't know if the procedure works for your issue, but I've done the procedure for another issue. Here is a link with pics of the procedure: http://www.timthurber.com/tims-volvo-si ... oor-noise/

You can buy a dedicated pre-loaded laptop on this forum or swedespeed in the classifieds. Sometimes they include the DiCE, other times not. Here: viewforum.php?f=40
or Here: https://forums.swedespeed.com/search.ph ... d=21782673

My first one I got from this guy; he's been great for support and shipped fast: https://forums.swedespeed.com/showthrea ... light=vida (DiCE sold seperately)

Really, though, get the VIDA/DiCE worth every penny. I also have the icarsoft for Volvo and it's great as a second, portable reader, but the VIDA has all the procedures etc on it, so it's for sure #1

[cn90]

O.P.,

I am posting this in case you need it before the winter.

2005 XC90 2.5T Tstat the easy way:
viewtopic.php?t=79031

2005 XC90 2.5T Heater Core the easy way:
viewtopic.php?t=82726

[vcsuri]

I don't know if the procedure works for your issue, but I've done the procedure for another issue. Here is a link with pics of the procedure: http://www.timthurber.com/tims-volvo-si ... oor-noise/

Thank you very much wanderdüne. This is the exact issue I'm having with the XC90. Once the heat is switched on, the blend doors with make the exact same noise as in the video of this link.

Did the calibration work to solve the issue in your case?