2005 Prius unusual AC and power issues

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by RetiredPrius, Aug 2, 2018.

  1. RetiredPrius

    RetiredPrius New Member

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    Good day all,

    Looking to see if anyone can give me some guidance/help in trying to fix my 2005 Prius, it has 205K miles. I'm here in Vegas and it was hotter than Death Valley yesterday, driving on the highway I noticed that the AC quit working and started blowing warm air. Thinking it may be low on freon, I stopped by O'reillys to see if I can recharge the freon. I got pure 134a and a hose with gauge, I hooked up the house to low side port but the gauge just go straight to max. I tried to charge it a few times but no luck. Decided to go home instead, while I was on the highway the VCS, brake, and red triangle came on with a loud beep, had to get off the highway. I had very minimal braking ability. I let the car sit and see if there is anything I can do but I didn't find anything. I tried to drive it again, this time the car slowed down and it won't move. I shut it off, waited 3-4 minutes, started it back up, I was able to put in drive and drove about 30 feet and the car died again. Waited another few minutes but the car won't go in to drive, only neutral. This time I used my insurance app to call towing so they could be on their way. I waited in the car for about 20 minutes, I tried to start the car again and this time it started and move, there were no lights on the dash, so I moved it to the side of the road. Had the tow truck tow it at home. This morning, I started the car and the AC worked, no lights on the dash, but I noticed that the power fluctuates, then the AC starts to blow warm air then about 2 minutes AC starts working again. I got into the MFD to check 12V battery, when the car is running or "READY", the charging voltage goes from 11.6 to 14.5, I can also feel the power fluctuations as the AC fan goes slow and then fast. When the AC fan goes slow, the charging voltage goes to 11.6 to as low as 10.9, then all of a sudden power surges and the charging voltage goes to 14.5v. BTW, I took the 12V battery to Oreillys and auto zone and they both said it's good. I'm hoping anyone here can maybe tell me whats causing the power fluctuations and the AC going in and out. Thank you all in advance for the help.

    Martin
     
  2. hchu1

    hchu1 Active Member

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    Check your inverter coolant system, is the coolant at proper level on reservoir, then check to see if inverter coolant pump is functioning. With you foot off brake push on/off button twice, go to inverter coolant tank take off top, look for fluid movement. No movement, dead inverter coolant pump, replace.
     
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  3. JC91006

    JC91006 Senior Member

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    Sounds like your inverter pump might have failed, causing the car to disable the AC, further causing the overheating of your inverter, and then disabling your car all together

    Hopefully no major damage was done.

    Check for codes. Or you can simply check for water movement in the inverter coolant reservoir while the car is READY. No movement would mean the pump failed.

    Next time your car disables itself. It probably would be best not to try and start it that many more times. Twice, maybe 3 times would confirm something is wrong
     
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  4. RetiredPrius

    RetiredPrius New Member

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    Hchu1 & JC91006,

    Guys, you both are right on the money. I went outside and started the car to “READY”, no significant fluid movement other than the small vibrations. I also put my hand on the pump and I can’t feel any whirring sound. It’s supposed to be running at all times when the car is on—in ignition or ready mode correct? Thank you to you both and this community for helping people like me, it’s much appreciated.

    Now I’m off to researching on how to replace it, hopefully not too difficult. Also, any recommendations on where to get a new inverter pump? Btw, I look at the service history record, the last time it was replaced was in 2012. My 12V battery was last replaced in 2013, so far it’s still a reliable car. Go Prius!
     
  5. edthefox5

    edthefox5 Senior Member

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    Since you started it up cold the next morning and immed had power fluctuation issues looks like the Inverter may be damaged since it didn't even warm up yet.

    Do as JC says check for movement of fluid in the inverter coolant reservoir when the car is in ready. If the pump is bad the inverter became severely overheated the day before and it failed. But most failed inverters the car wont even go into ready so......

    OR.

    If you have fluid movement the other thing that kills the ac first thing is a bad hybrid battery. When the hybrid battery is unable to provide minimum power it puts the car into LIMP MODE and shuts off all high power devices which is the ac.
    During this did you ever look at the hybrid battery charging meter on the mfd? If the battery is going from full to empty real fast you have a bad hybrid battery. If its the original hybrid battery I would not be surprised especially if lately your mpg's are real bad.

    The car has thrown alot of codes and you need to have the codes read and it will tell you exactly what failed. The auto store will be unable to pull the codes you need as most are not able to pull hybrid codes with there cheesy obd testers.
     
  6. RetiredPrius

    RetiredPrius New Member

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    Yeah, I really hope the inverter isn't damage, I do know for a fact that the inverter coolant pump is not working as I've posted above. When it happened yesterday, the battery state on the MFD was indicating halfway charge. I also forgot to mentioned that when I started the car this morning, I drove it around 2 blocks and the battery SOC on MFD went to about 4 bars with no issues. No issues when I drove it and no lights on the dashboard yet. The only thing I really noticed is that the power seems to fluctuate indicated by battery charging rate fluctuating (from 11.2 to 14.3 and back and forth) at the same time as the AC blower fan speed also fluctuates. The AC also went to warm and then cold and then warm again. I'm crossing my fingers the inverter is okay and that I just need to replace the inverter coolant pump. Thank you again for the feedback.
     
  7. edthefox5

    edthefox5 Senior Member

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    Sounds like the dc to dc part of the inverter is damaged or your 12 volt battery has a shorted cell. Either way the car will see this immediately and throw a dash board light and a code. Sounds like the Inverter is bad but cant understand how its capable of charging the hybrid battery while your auxiliary components are fluctuating up and down. The car sounds like its in limp mode. Lots of codes on the dash.

    Oreillys or any other parts store as far as I can tell on this site is incapable of harvesting hybrid codes. You must use a toyota techstream capable obd code reader. Either buy one or take it to the dealer. Btw the auto parts stores are incapable of testing the battery too. Cant tell you how many people on this site say there 12 volt battery is good and was tested and turns out it has a bad cell.

    Test the 12 volt yourself. Get a voltmeter. With car OFF check the 12 volts at the front jump points not in the back. Write that down.. Then with car OFF turn on the headlights in high beam. Leave them on for 5 minutes. With the lights still on at the end of 5 mins check the 12 volts on the front jump points. Tell me those 2 voltage numbers.

    Btw, if thats the original hybrid battery I would be pretty surprised its not on its last legs. Its 13 years old. 200+K miles and lives in a very hot climate. At the very least its going to be pretty corroded. So no matter what the outcome is your looking at a new battery soon.

    I still think the hybrid battery is bad here and hammering the inverter.
     
  8. RetiredPrius

    RetiredPrius New Member

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    okay, thank you for the feedback and will test the 12V bat tomorrow and will report back. In the meantime, I went ahead and ordered the inverter coolant pump and a gallon of SLCC so I can replace the pump and flush the system. In the last 2 days, I've been turning it on and off and drove it around the block once just to see if any waning lights come on, nothing except that the inverter pump is not working. The AC now works too, but don't know for how long. It still doesn't explain the fluctuating power even though there are no warning lights. Yeah original battery for sure and the hot climate doesn't help. My plan of action is to replace the inverter pump, flush and fill the system and then see if I still get the fluctuations. If I get the fluctuations but no warning lights still, then I will drive it for longer periods...and then go from there. Last resort would be to go to the hybrid center here in Las Vegas and see if they can pull the codes as they do it for free. I will keep you all in the loop, thanks and happy driving!
     
  9. RetiredPrius

    RetiredPrius New Member

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    Ed,

    So I tested the battery today and did exactly as you said..with the car off the battery measured 13.4v, then I left the lights on and in high beam for 5 minutes...after that, the voltage measured at 12.2v, is this a good battery still? Please let me know and thanks for the help.
     
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