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2008 AC issues

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by noname87, Jul 21, 2016.

  1. noname87

    noname87 Junior Member

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    Vehicle:
    2008 Prius
    Model:
    Two
    I have a 2008 standard Prius with 100K miles. Today the air temperature was 91 degrees. I was driving on the highway at about 70 mph between 12-2 pm heading north and also east. I had the AC on full blast with the setting on inside air and the air direct to the dash vents. I just could not get the car comfortable in the front. I would be surprised if the inside temperature was below 80. The system was blowing cool air. Even with two of the four vents closed, It didn't seem like I wasn't getting the usual amount of air flow.

    Three plus hours later, I was driving the car after it was sitting for two hours. The air temperature (on the display) was 81 degrees. It was now between 5-7 pm. The AC had no problems and was able to maintain a decent temperature with normal air flow. The fan speed was set on a lower setting. Also set to inside air. Later on (7-10), the temperature was 75 and the inside temperature was chilly.

    My guess is that 1) the solar load was overheating the car and 2) maybe the main battery fan was cooling the main battery and dumping the heat into the cabin via the vent in the rear seat. I did not hear the fan but the AC fan was on maximum. I did notice that the fan was running yesterday until the car cooled down.

    Any ideas? Is the AC system undersized and unable to handle high outdoor temperatures? If that is the case, I am glad I do not live in Florida. I will have the charge level checked but what else needs to be checked.

    Also I need help. My wife is convinced that this happen one time when the small battery in the back was failing. I tried to explain that this doesn't make sense but I am only a mechanical engineer. As a CPA, she is convinced that this is a factor. Does this make sense? As I understand it, the small battery supplies the power to energize the relay that connects the main battery to the electrical system and also to power the accessories when the power is off.
     
    #1 noname87, Jul 21, 2016
  2. JC91006

    JC91006 Senior Member

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    You should change your cabin air filter
     
    #2 JC91006, Jul 21, 2016
  3. kenoarto

    kenoarto Senior Member

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    "Even with two of the four vents closed, It didn't seem like I wasn't getting the usual amount of air flow."
    Do you do this to try to cool or heat faster?
     
    #3 kenoarto, Jul 21, 2016
  4. noname87

    noname87 Junior Member

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    The filter was changed recently but I will check it again,
     
    #4 noname87, Jul 21, 2016
  5. noname87

    noname87 Junior Member

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    My daughter has asthma and was having trouble breathing. I was trying to get more air flow to her. This is not how I normally use the AC vents. However, we do keep the air set on inside air when she is in the car.
     
    #5 noname87, Jul 21, 2016
  6. bisco

    bisco cookie crumbler

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    maybe your a/c needs a recharge.
     
    #6 bisco, Jul 21, 2016
  7. JC91006

    JC91006 Senior Member

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    The rear 12v battery only starts the electronics in the car, does very little else once the car is in ready mode.

    I feel the ac a bit undersized when the temperature is extremely hot. Worse in my black prius
     
    #7 JC91006, Jul 21, 2016
  8. kenoarto

    kenoarto Senior Member

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    All of my family suffers from asthma. If the air flow is actually increased by closing vents, I'm thinking fan or duct obstruction. Have you used a thermometer to test each vent?
     
    #8 kenoarto, Jul 21, 2016
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I live in an area that routinely has 110+ degrees F summer high temps, and I have no problem with the Prius air conditioner satisfactorily cooling the passenger cabin. Since you have a problem, my idea is that your air conditioning system has a tiny leak. Look at the sight glass when the air conditioner is running, for bubbles. If you see this then the system needs an R-134a recharge.

    Since you are a mechanical engineer you should be able to do the recharge yourself if you get a set of low/high pressure gauges and a can of R-134a. Make sure the refrigerant is pure, and does not contain any compressor oil within.

    Do not use gauges that had previously been used on non-Toyota hybrid vehicles. The concern is to prevent contamination from the typical AC compressor oil used in non-hybrid vehicles, which will conduct electricity.

    I've previously posted the correct high/low pressure spec for the system and you can also access factory repair manual info at techinfo.toyota.com
     
    #9 Patrick Wong, Jul 23, 2016
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