HV cooling fan question

Discussion in 'Gen 2 Prius Technical Discussion' started by robert Kwasny, May 7, 2021.

  1. robert Kwasny

    robert Kwasny New Member

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    My 2005 Prius HV cooling fan only works properly with hybrid assistant app or doctor Prius app running. Would that narrow down where to look for the problem component? Any thoughts or suggestions would be appreciated.
     
  2. PriusCamper

    PriusCamper Senior Member

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    If it works in those apps, then it works in general. The fan isn't designed to work on a regular basis, only when stuff starts going wrong. If the fan is not on then nothing is wrong... To be sure keep an eye on the temperature readings in the apps.
     
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  3. robert Kwasny

    robert Kwasny New Member

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    I should have explained better without the apps running temperature climbs to 115 degrees and no fan
     
  4. PriusCamper

    PriusCamper Senior Member

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    I use a thermal imaging camera on battery packs to find overheated cells, so you could try that... And it is a bit concerning the fan doesn't start at 115, but if it starts at a slightly higher temp than that you should be ok. Majority of all my experiences with fan running are when car throws an error code and goes into limp mode. So until it throws an error code, it might not be anything to worry about.

    Is your fan clean?
     
  5. robert Kwasny

    robert Kwasny New Member

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    Fan is clean. Just finished rebuilding pack. No error codes. I thought fan was supposed to come on at 96 degree.
    Thats when it comes on when running hybrid assistant.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Can you hear it running?


    I ask cus our 3rd gen is very quiet, I’ve never heard it. A few years back I had a scangauge connected, and it would report it running, various speeds. But yeah, couldn’t hear it.
     
  7. PriusCamper

    PriusCamper Senior Member

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    Oh good... If you've the skills to rebuild the pack then we can troubleshoot with you...

    --The relay system that gets the fan going is very slow and clunky, I've often let my impatience interfere with testing it via hybrid assistant, as well as by temp readings.

    --Check the white plug that mounts near where the cooling fan is. It has 4 wires going in and out even though the plug could handle way more wires. These are known to corrode and throw an error code for battery fan voltage irregularity

    --Hybrid assistant lets you control all the fan speeds. Have you confirmed that it works at all speeds?

    --I've rebuilt packs before that tested great but had one cell that was running hot and before I got a thermal imagine camera I'd be unable to find those ones, so that might be the source of your problem. If you have a friend who does home inspections, they have a thermal camera. Or a Seek Thermal camera is the biggest sensor for lowest price.

    --Are all temp readings similar / accurate when viewed in Dr. Prius App?

    --You're located in an area with high temps, so you could easily test how hot it has to get for fan to operate, though that's not so good for the battery

    --Forget about it till you get more data / lights / error code
     
  8. robert Kwasny

    robert Kwasny New Member

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    I have already tested the relay near the fan and also took apart the white connector you speak of. There was a slight amount of corrosion on one contact which I have cleaned nothing like some of the photos I've seen of those with high amount of corrosion. The fan runs at all speeds and temperatures are all within one degree. I think I'm going to cut that connector out and splice wires just to eliminate that. There is some sort of sensor or relay inside the exhaust duck was waiting to see if I could find the source of the problem before I take that apart do you know what that does?
     
  9. ChapmanF

    ChapmanF Senior Member

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    If the fan spins at all speeds when you tell it to via an app, all the necessary electrical circuits through those connectors are already tested. The app doesn't spin it by telekinesis.

    When you're not commanding it via the app, it's the ECU that decides when to run the fan and what speed. It seems like the gist of this thread is that you and the ECU are not agreeing about when it ought to run?
     
  10. robert Kwasny

    robert Kwasny New Member

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    Thanks
    So if thats the case only fix would be new ecu. maybe I will run app on permanent basis.
     
  11. PriusCamper

    PriusCamper Senior Member

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    At this point it's clear that the only problem with your cooling fan is that you're trying to fix something that isn't broken... The only fix for these kinds of problems is for something else to go wrong so you lose interest in this on. I'm placing my bet on a bad cell in your rebuilt pack that's running hot that you can find with a thermal cam.
     
  12. Grahams Number

    Grahams Number New Member

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    I installed the custom PID for Torque Pro found on this site to control/command fan operation. I picked speed 5 which I can hear from the front seat. By using a piece of paper I can see it is creating vacuum on the vent. The fan is clean and operates properly.
    When driving today it seemed the temperature rise was same as always. Intake temp = 74 F batteries started at 76.9 F and after 30 minutes of urban driving they were at (sensor 2) 97.8F. This is a year old OEM battery pack that appears to be healthy. SOC was around 71% after a long, down hill, regen before getting home.
    In the winter I see it start dropping even on speed 1 when I'm not in stop and go traffic but the fan turns off at 90 F so I just go in a loop between 90-99 F. In summer...temps rise fairly quickly and start at higher ambient than in winter. (Car is garaged) I never go over 100 F but I don't have to drive far. I would think twice, maybe three times about taking her on a trip.
    The reports I have read here are totally different than what I have experienced. Someone suggested the battery air dams in my pack may be missing or improperly installed. All I can tell is that the fan is drawing air and blowing it somewhere.
    For those watching battery temperatures...what affect does the fan have on battery temperature. Does the reading drop quickly? Does it still drop temperature when car is stationary? On a 90 degree day does the battery temperature quickly, or reasonably quickly, drop when the fan comes on?
    Many who post here say their pack never goes over 100 F which I find incredibly hard to believe...
     
  13. TMR-JWAP

    TMR-JWAP Senior Member

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    I've seen plenty of very low quality work performed on battery installations. If a new OEM pack was installed, then yes, it's incredibly important to transfer the correct parts as required from the old assembly to the new. If not? Cooling problems are heading your way. Much less the air ducts being mounted properly, or not being installed at all. Hard for a fan to cool a battery when no duct is mounted between them..........

    personally, I wouldn't be worried a bit if my battery were over 100F in the summer heat.

    The battery protects itself with charge control limits and discharge control limits based on battery temperature and SOC.
     
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  14. robert Kwasny

    robert Kwasny New Member

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    After further examination my fan only runs at speed 6 with hybrid assistant app running. Would that indicate a problem with one of the relays or other fan components?
     
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