MPG drops 50% when AC Blower is On

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by bnzjamin, Dec 4, 2018.

  1. bnzjamin

    bnzjamin New Member

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    2013 Prius c
    Model:
    Three
    To all readers and contributors, thank you in advance for your time and help, now and in the past. Long time lurker here, but I finally made an account today after hitting nothing but dead ends on this issue.


    Short Story:

    2013 Prius C Three. 147,000 miles. MPG averages @47-49 (up to @60 if trying) when AC blower is off. This drops to 27-33 MPG when heating or cooling is on. MPG gets worse as I increase the speed of the fan. Any ideas?


    Long Story:

    This issue started around 135,000 miles. The dealer advised that this was just the cost of using the AC in the summer and that I had just never noticed. They would not offer any possible solutions unless a CEL came on.


    Fast forward 4 months to @146,000 miles. I popped a CEL. The Hybrid Battery was dead. The car still ran fine on the gas engine. Over @200 miles I was getting @30 MPG with no AC, closer to 20-25 with the AC on. Despite the CEL, the car never stopped running fine on gas only.


    Toyota quoted @$4,000 to replace the battery. I requested a good will discount from corporate and they only came down 15%. And they would not guarantee that this would fix my original MPG issue.


    After reading reviews, getting multiple quotes, and understanding the risks, I opted for a rebuilt battery swap from a shop in LA. $1,300 with a 3 year 45,000 mile warranty. And I paid with my AMEX just in case they wouldn’t stand behind their warranty.


    Now, about 1,000 miles into the new battery, I’m back where I started this summer, perhaps slightly better. The car works nearly as efficiently as when brand new, as long as the AC blower isn’t on. Turn it on, and I’m getting at least 100 miles less per tank.


    The dealer and 2 local shops will only recommend putting in a new factory hybrid battery for @$3000-$4,000. Only then will they consider diagnosing any potential, but likely imaginary they say lol, additional problems.


    The only thing I can think of is to replace the AC blower motor and see what happens. Any advice?
     
  2. PriusCamper

    PriusCamper Senior Member

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    Well... First step would be to bring your car to an automotive AC specialist and get an estimate. There should be plenty of them in your part of the country... I'm thinking, maybe it's the compressor? Also I'm a bit suspicious that your previous battery was totally dead and you were only running on engine power because your gas mileage would be much lower and you would have barely enough power to accelerate onto the freeway.

    Do you have CEL error codes that first came up when this fiasco started? Sounds like the mechanics at your car stealership were being lazy and greedy and weren't very thorough about checking all the possible issues that could be related to this problem.
     
    michael.sfo likes this.
  3. cnc97

    cnc97 Senior Member

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    I’m thinking an inverter/converter issue. The inverter/converter powers the AC system. There is not enough energy to charge the HV battery and run the AC. It’s less resistance for the electricity to power the ventilation system.
     
    PriusCamper likes this.
  4. PriusCamper

    PriusCamper Senior Member

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    Yea... That would make sense... But knowing what the exact CEL codes are is key...
     
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