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Thread: Nil heat from HEVAC

  1. #1
    Join Date
    Apr 2010
    Location
    Lower Hunter Valley NSW
    Posts
    311

    Nil heat from HEVAC

    Hey fellas, now that autumn is finally here and the mornings are colder, I have the need for cabin heat. I have nil heat. Not even warm.

    I have hot coolant in the heater core and recently replaced my HEVAC blend door motors. I have nil errors showing and of course no book symbol.

    Anyone have any clues?
    Current: MY99 Range Rover HSE with 5.0L V8
    Past: MY01 Discovery V8 - drowned , MY03 Discovery HSE V8 - sold

  2. #2
    Join Date
    Oct 2007
    Location
    Williamstown, Victoria
    Posts
    555
    If it was a long time since the old blend motors failed, the flaps themselves could have become stuck due to non use over an extended period of time, although if they were working fine prior to the failure of the old belnd motors, they might be ok.
    Have you tried the ac to see if cold air comes out?
    Sometimes the book symbol will not appear for a while even if there is a fault.
    I'm assuming the fans are working and the wiring is correct for the new motors.
    I would check hevac fuses 8 & 17 as a starting point, they can cause these issues.
    If that makes no difference, I'd also check the heater core and hoses to make sure there is not a blockage somewhere.
    I would disconnect the heater hoses in the engine bay and give it a flush out with a hose just to make sure that is not the issue.
    Even though the heater core is hot, a partial blockage could affect things.
    Let me know how that goes!
    Cheers, Pete.

  3. #3
    Join Date
    Apr 2010
    Location
    Lower Hunter Valley NSW
    Posts
    311
    Thanks mate. The AC goes great and I have re calibrated the blend door motors with my RSW EAS thingy. Fans are great, ice recently replaced one plus the their relays.

    There is definitely hot coolant getting to the core so I'll try flushing the core and see if I unblock anything hiding in there.
    Current: MY99 Range Rover HSE with 5.0L V8
    Past: MY01 Discovery V8 - drowned , MY03 Discovery HSE V8 - sold

  4. #4
    Join Date
    Oct 2007
    Location
    Williamstown, Victoria
    Posts
    555
    If it's not a blockage, it has to be a flap not doing what it's supposed to.
    I had a/c only coming out of the passenger side vent and the book symbol appearing on mine. Hooked up the faultmate, and got a right hand blend motor short circuit fault.
    Interestingly, I cleared the fault and everything started working again. I have read if the book symbol is showing, the system won't work properly until the fault is cleared.
    I was only doing local trips for a couple of weeks and all was fine, but when I did a longer trip, the fault appeard again, and only a/c out of the passenger vent again, same thing with heat.
    So mine wouldn't throw a fault until I took it for a longer drive.
    If you could get a fault to appear, at least that would point you in the right direction to solving the problem.
    Just out of interest, are you mostly doing shorter trips at the moment?

  5. #5
    Join Date
    Feb 2013
    Location
    Gosford, NSW, Australia
    Posts
    2,394
    I agree that if the core is hot then it's most likely and issue with the flaps or blend motors. The nanocom lets you operate the motors so you can see what's going on, not sure if you have a nano though.

    Steve
    MY96 4.6 HSE P38. Niagara Grey; "The Phoenix"
    MY99 4.6 HSE P38. LPG, Blenheim Sliver; "Voldemort" burnt to a cinder
    MY79 RR Classic, Gone, MY57 Series 1 SWB, Long gone
    P38 write ups and info on my website http://p38.hts.com.au/

  6. #6
    Join Date
    Feb 2013
    Location
    Gosford, NSW, Australia
    Posts
    2,394
    Quote Originally Posted by PeterH View Post
    I have read if the book symbol is showing, the system won't work properly until the fault is cleared.
    I have a LH reticulation motor fault, the bastard right up under the dash, and it seems to make the book symbol come and go, but apart from the that the system seems to be working OK.

    I could see that a blend motor fault might make things go a bit haywire though!

    Racking my brains about barnacus issue to little avail; it's a weird one

    The other nice thing about STC3266 motor is that is genuine only and a snap at around only 90 each

    Steve
    MY96 4.6 HSE P38. Niagara Grey; "The Phoenix"
    MY99 4.6 HSE P38. LPG, Blenheim Sliver; "Voldemort" burnt to a cinder
    MY79 RR Classic, Gone, MY57 Series 1 SWB, Long gone
    P38 write ups and info on my website http://p38.hts.com.au/

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