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Overheating, radiator fans aren't running.

Discussion in 'Gen 2 Prius Technical Discussion' started by MrSteveB, Jul 15, 2017.

  1. MrSteveB

    MrSteveB Member

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    I've been reading all night and morning on here and haven't found many answers specifically on causes of the rad fans to stop working.
    I got the red triangle last week in traffic while it was quite hot out and the AC was running full blast. Upon inspecting the condenser I realized it was incredibly neat up especially on the lower half from rocks and bugs and whatnot. Last weekend I replaced the condenser to free up airflow to the radiator and figured that was my reason for the overheating issue since hardly any air was able to get to the inverter part of the radiator. I haven't recharged the AC yet but it's all hooked up.
    I've been driving regularly with no issues until yesterday while o was driving around in Colorado Springs. Heading up some of the longer mountain roads there were no issues. Until of course at the top I had to stop and shortly after I got the triangle again. That's when I realized it must be radiator fan issues since the car runs great as long as I'm moving. I drove back home with no issues again after resetting the ecu. This morning I checked the RDI and ECU-IG fuses and they were fine. Inverter pump is working. Radiator coolant is full in the overflow tank and the radiator. It's gotta be the fans. So I'm trying to figure out how many coolant temp sensors we have and where they are and also how many fan relays and where they are? I did run my engine in diagnostic mode where the engine won't shut off this morning for around 7-10 mins and the fans never kicked on although I could smell that the engine was getting hot. Oil is not milky and the coolant being full makes me rule out head gasket issues at this point.
     
  2. bisco

    bisco cookie crumbler

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    maybe thermostat? there should be a diagram of the fan logic at toyota tech info.
     
  3. MrSteveB

    MrSteveB Member

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    I would guess its not the Tstat since the car has no issues when it's moving and has that airflow over the radiator. Although if I have to replace anything that actually has to do with the coolants where I'll have to bleed it, that would be a great time to replace the thermo since it's pretty old now.
     
  4. ChapmanF

    ChapmanF Senior Member

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    I have tested really old thermostats in hot water with a thermometer and found them to still open at exactly the temp stamped into the flange. I guess they can go bad but not sure how commonly; not all that much to go wrong with a wax pellet that expands.

    If you've confirmed the fans aren't running when they should be, there's your diagnostic focus. You got the right advice from bisco: the wiring diagrams at techinfo.toyota.com will answer all your questions about sensors, relays, and wiring for the fans.

    -Chap
     
  5. valde3

    valde3 Senior Member

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    There are 2 fans they are controlled by 3 relays. FAN 1-, FAN 2-, and FAN 3-relay. Fans get there power through 30A RDI, and 30A CSD FAN fuses.

    -AC pressure switch, Engine control unit, or AC-control unit can turn the radiator fan (just one fan) ON (with FAN 1-relay).
    -Inverter coolant temp switch, or AC-control unit can turn bough fans to low speed (with FAN 3-relay).
    -AC-control unit can turn bough fans to high speed (with FAN 1-, FAN 2-, and FAN 3-relays).
     
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  6. Kevin_Denver

    Kevin_Denver Active Member

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    Your reasoning makes sense, but I would want to confirm before replacing the fan. A bad thermostat or water pump that still kind-of works could yield the same problem. The thermostat when functioning correctly starts to open when the water temp is at 85C, and is fully open at 92C. The radiator fan turns on at 95C. However the Atkinson engine is so efficient that when the car is stopped and idle, it's likely you're not getting up to the 95C mark to trigger the fan just from idling as might occur in other cars.

    One way to diagnose this is an OBD tool that can read the water temperature. You follow the procedure to force charge the battery, and rev the engine to 2-3k for several minutes until the water temp reaches at least 95C and confirm that the fan isn't starting. You can do this with a scanguage or with Techstream via a mini-VCI cable. I'd want to confirm that the water temp is indeed reaching 95C and the fan not starting as expected.

    Also old thermostats are designed to fail open. Them failing closed does occur, but is much more rare.
     
  7. edthefox5

    edthefox5 Senior Member

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    The belt probably fell off.
     
  8. 05PreeUs

    05PreeUs Senior Member

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    Your process of elimination is good, I agree it seems like a fan issue. For testing purposes, you can jump (with a fused wire) the B+ and Fan terminals of the relay SOCKET to power the fans, if they spin you most likely have a control issue from the ECM to the fan relay(s).
     
  9. fotomoto

    fotomoto Senior Member

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    LOL.

    Or loose or worn to the point that it's not turning the water pump enough for adequate flow. Also if there is a lot of green residue on the lower edges, it's coolant leaking from a bad water pump. Check the easy stuff first.
     
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  10. 05PreeUs

    05PreeUs Senior Member

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    Low water flow will NOT present at low engine speeds or at idle, but under higher loads and highway speeds - exactly where he DOES NOT report any problems.
     
  11. edthefox5

    edthefox5 Senior Member

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    Don't know how you can meaure water flow when the car is moving.
     
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  12. MrSteveB

    MrSteveB Member

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    Which slot of the 4 will the positive wire go to for these terminals?

    I checked the water pump the best I could without taking the car apart and it appears to be dry. The belt was replaced last summer and appears to be in decent condition still, I also wiggled the pump shaft back and forth and felt no play in it. I've never seen a belt go bad in just one year but I'm going to try to get a better look at it to check for cracking or reasons it wouldn't spin the water pump.

    Question: I know cars with regular AC compressors have the compressor clutch which can sometimes prevent the compressor from running without it being charged. If my AC is not charged yet and I run the AC with the car on, will the radiator fans run, or will they remain off because the car knows there is no charge? I ask because I turned the AC on last night to check for current at the fans and there was none. So if the fans would still spin even without the charge then I'm now sure there is no power getting to the fans.
     
  13. edthefox5

    edthefox5 Senior Member

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    No there's a pressure switch and compressor will not run if not charged and fans will not come on either.
     
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  14. MrSteveB

    MrSteveB Member

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    Okay thanks. I'll have to do the relay jump to check for the fan status. thanks.
     
  15. 05PreeUs

    05PreeUs Senior Member

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    Low/no AC charge will NOT prevent the fans from working to control HSD or Engine Temp, only AC pressure.
     
  16. MrSteveB

    MrSteveB Member

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    I have to say this is getting rather annoying. I had my AC charged today and it's been confirmed the radiator fans work great. I also had the tech run my diagnostics with techstream and he confirmed the fans come on when the water temp is at 181 or so. He also confirmed the 3 way valve is working and he found no codes that would give clues to the issues. Ran the AC on medium the entire way home, parked the car and turned it off, with no lights on the dash. Grabbed some lunch and when I came out to go to work the dash was lit up with the typical triangle!. He said he didn't think the symptoms of this issue sounds like overheating but it only happens on hot days when the AC is on or a lot of city driving on said hot days. I bought a techstream myself but found out today that it won't work on windows 10 which is just fantastic. The guys at the hybrid shop were really knowledgeable so I'm kinda screwed until I can get a computer to run techstream and pull the codes and diagnotics once the red triangle pops on since the codes apparently disappear upon pulling the ground of the 12v.
     

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  17. bisco

    bisco cookie crumbler

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    speaking of the 12v, did we already discuss that?
     
  18. dolj

    dolj Senior Member

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    You can create a Win XP or Win 7 (32-bit) virtual machine within windows 10 and install TS in that.
     
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  19. edthefox5

    edthefox5 Senior Member

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    Its just the red triangle there nothing showing on the mfd also like a car in the upper left corner looks like a turtle?

    I think you have other issues that may not be ac. Its either the 12 volt battery or the hybrid battery would be my long guess.
    Got to harvest the codes the car is telling you exactly what its unhappy with.

    You can buy a XP laptop all day long on craigslist for cheap.

    If I had a real nice Win10 laptop I would not use it to read obd...it would probably get the hell beat out of it jumping in and out of the car. I got 2 beater dell d730 xp's for that.
     
  20. MrSteveB

    MrSteveB Member

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    I've heard of that but I can't do it since the laptop isn't mine. I'm going to do what edthefox below you said. I'm just going to buy an ancient pos junk laptop with xp as the os and put it on there. Thanks for the suggestion.


    Agreed it's not the AC, but the AC being on is contributing to the issue. It happens whenever the AC is running which makes me still think it's some kind of heat issue. I did get a tiny red car with the ! point right through it last time this code came up. Also, I was thinking about your idea and just buying some old pos laptop on Craigslist and using that. I really hope its the the HV battery but it could be the 12v since that's a couple years old. However when in diagnostic mode that 12v does register 14.1 I believe which is in the normal range. I really need to get that computer and replicate the error.