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  1. #1
    Join Date
    Nov 2014
    Location
    USA
    Posts
    64

    Default Heating & AC = Cold or Hot, nothing in-between

    The temperature control on my 2003 XC70 has recently stopped working correctly. Basically, it's full cold for most of the control settings until you turn it all the way to maximum heat, at which point it switches to full heat.

    Is this a common problem with a known solution?

  2. #2
    Join Date
    Feb 2010
    Location
    Virginia Beach
    Posts
    4,013

    Default

    You may have a broken sensor in the climate control module. If you’re lucky - there is a bunch of dust in the sensor port, which you can see behind the little horizontal lines in the climate control panel. Try blowing it out with a computer duster. Be gentle, don’t break the thermistor
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  3. #3
    Join Date
    Dec 2009
    Location
    GA
    Posts
    1,402

    Default

    Quote Originally Posted by Silvestris66 View Post
    Is this a common problem with a known solution?
    I agree a temp sensor could be the cause, careful with the interior air temp sensor! - I've replaced evap temp sensors in Volvos - and an Infiniti to solve that problem. A compatible scan tool will be able to monitor those sensors to make sure you are replacing the correct part.

    https://www.fcpeuro.com/products/vol...665118#fitment

  4. #4
    Join Date
    Apr 2017
    Location
    San Diego
    Posts
    139

    Default

    Said interior temp sensor thermistor sits right behind that vent in the climate control head unit. The wires are really fine, and it's mounted with the wires pretty taught, so it takes very little contact force to break the wire. Don't go poking deep through those vent slots to dig out the dust. 1-2 mm deep at most and stay parallel to the vents with a simple straight tool. No trying to twist a bent tool and dig behind the openings.

    It's a fairly simple operation to pull the climate control head unit, disassemble it, and check the sensor. Mine was broken. I soldered in one plucked out of a salvage yard head unit, which was a challenge due to the fine wires. Having said that, I did not have the same symptoms you're having. It was a while ago, but I think I was getting heat at the wrong time, which was why I went digging for the sensor. I don't think it's completely fixed. I don't drive the XC a lot, but I think I still got some undemanded random heat here and there.

    Brett

  5. #5
    Join Date
    Feb 2010
    Location
    Virginia Beach
    Posts
    4,013

    Default

    I’ve done an evap temp sensor also. Inexpensive. Not hard to replace. VIDA will help you narrow this down…
    Current Fleet:
    2016 Tundra Crewmax 4WD 1794
    2005 MB S600 (110K, Michelin AS3+, LiquiMoly 0W40)
    2002 V70-XC (272K, Castrol Edge 0W40)
    2002 V70-T5 (215K, IPD bars, Bilsteins)
    2001 V70-T5 (110K)
    1932 Packard Sedan (straight 8, dual sidemounts, original paint and interior, Shell Rotella 15W40)

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