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Weird AC Issue

Discussion in 'Gen 2 Prius Main Forum' started by nownow, Aug 7, 2018.

  1. nownow

    nownow Junior Member

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    Okay so I've searched this and I can't come up with something that makes sense.

    2008 with 290k (280k mine). When first started on a hot day, the vent to the right of the center screen will blow cold and the vent to the left of the center screen (and the one by the drivers door) blow warm for quite some time, almost as if they're just recirculating. Everything I've seen suggests the vents on either side of the center screen are connected behind the screen, but the temperature for probably the first 10 minutes is drastically different.

    AC in general is weak above 90F outside temp but can be pretty cold under 85F outside. I'm kind of hoping for a quick stupid fix on the AC issue, and probably wouldn't take it in for a full AC service until next spring at this point, if at all, mainly due to potential cost...

    Honestly I'm sorta nursing this car along until either the engine (1qt every 1500 miles) or the battery decide to go. It's been a great car, the exterior looks pretty good for black, (thanks to a garage and faithful waxing) and the interior leather is in amazing shape, honestly. I just can't see putting a lot more money into it.
     
    #1 nownow, Aug 7, 2018
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  2. ericspoor

    ericspoor Member

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    the cars inverter provides power to the electric AC system via the battery. the inverter is cooled via its own coolant line seperate from the engine. if the inverter coolant pump is weak, the coolant wont flow fast enough across the inverter heatsinks and transfer heat away from the inverter quickly enough. the car will sense this, and throttle the AC to prevent the inverter from overheating trying to power it. given this, i wonder if your inverter coolant pump is weak. the pump ususally lasts about 100k miles so if you got it replaced during the recall its probably about time for it to fail again. the pump itself is $140, you can replace it yourself without having to flush the inverter coolant (which would make it a bigger job), if you find a diy video. otherwise its $500 at the dealer including labor, or $275ish at an independent shop that knows what theyre doing.

    to test if the inverter pump is weak or out, open the hood, insert the key and put the car in ready mode. remove the cap on the inverter coolant resvoir (upper left of the inverter, the big silver box to the right of the engine). if theres turbulence in the fluid, its working, otherwise the pump is weak or out and that could be your problem
     
    #2 ericspoor, Aug 7, 2018
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  3. nownow

    nownow Junior Member

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    Hmm - that's an interesting point. The pump was replaced at 88k (failure) and 145k (recall campaign) so yeah, I suppose it's probably getting to be about time. Not something I'm looking forward to doing, but certainly not something I'm paying to have done.

    Why would one vent be significantly colder than another, though - that's the part I I find particularly odd...
     
    #3 nownow, Aug 7, 2018
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  4. ericspoor

    ericspoor Member

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    that part i have no idea. it takes about 30 seconds to do the pump test so i figure its worth just seeing if that might be it before trying to go too deep on diagnostics
     
    #4 ericspoor, Aug 7, 2018
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  5. nownow

    nownow Junior Member

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    Thanks - I can check that today or tomorrow.
     
    #5 nownow, Aug 7, 2018
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  6. Raytheeagle

    Raytheeagle Senior Member

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    The blend doors could be a bit worn out, leaving one open and one in a different position ;).

    You can check the actuators for those and see if they are moving or are stuck in place:(.

    Good luck and keep us posted (y).
     
    #6 Raytheeagle, Aug 7, 2018
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  7. ChapmanF

    ChapmanF Senior Member

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    There aren't separate doors per side. Gen 4 maybe (did they call it "S-flow" or something?). Not Gen 2 though.

    If there's a mouse nest on the evaporator or in the housing somewhere, it might not be completely uniform from side to side. Not all mice are sticklers for symmetry.

    -Chap
     
    #7 ChapmanF, Aug 7, 2018
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  8. nownow

    nownow Junior Member

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    Gosh, I'm not sure this car is in one place long enough to add a mouse, but I'm sure obstructions are possible. Is the duct system at all easy to get to at the evaporator (like to check for obstructions, etc) or is it a full dash disassemble?
     
    #8 nownow, Aug 8, 2018
  9. nownow

    nownow Junior Member

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    FWIW - There is plenty of turbulence in the inverter coolant reservoir. I'm guessing that's not the issue now, but I'm sure that pump will rear it's head at some point in the near future.
     
    #9 nownow, Aug 9, 2018
  10. ericspoor

    ericspoor Member

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    thats good to hear. if i were you id check it maybe once a week to see if you can notice the turbulence getting weaker/less "slosh-y". on my prius i was able to catch it when it was getting weak, if i was driving when it finally went out i wouldve possibly cooked the inverter to the tune of $3000 or whatever it is to replace it
     
    #10 ericspoor, Aug 9, 2018
  11. nownow

    nownow Junior Member

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    I drove this one about 30 miles on a 90+ degree day when the pump went out (or at least got bad enough to throw the code) the first time. After I figured out what I did I was shocked I hadn't damaged the inverter. That was 200k ago...
     
    #11 nownow, Aug 9, 2018
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