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05 - AC fades in and out

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Diotima, Sep 6, 2013.

  1. Diotima

    Diotima Junior Member

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    all,

    I've got AC problems. :( I've done searched and read a great many threads, but I didn't find a scenario that matches mine.

    My blower is fine. My touch screen works normally for the Climate options. What's happening is that sometimes the AC blows cold air and sometimes it doesn't. It fades from one to the other and back over the course of about half an hour.

    The most common pattern is that I have AC for about 3-5 minutes after I start the car. By the time I hit the freeway, the air has become warm and occasionally stale smelling. At 15 to 20 mins in, the AC becomes cold again. Sometimes it stays cold until I get home (40 mins total drive time) and sometimes it cuts back to warm after 5 or 10 mins.

    The shift isn't sudden, and it isn't accompanied by any noises. The air just warms up or cools down.

    Second most common pattern is that it blows warm when I turn the car on, cools down after 15 mins or so, and stays cool until I get home.

    I know I will probably have to take it to the dealer, but I'm looking for a possible yea or nay on whether this sounds like the compressor, or what else it might be so I can plan for the budget hit. :(

    I have checked my air filters - no problems there.

    I installed an Optima battery in Feb of '10.

    The car has 89k on the clock. It suffered front end damage in as the middle car in a 3-car sandwich, but that was 4-5 years ago and the AC worked fine until maybe a month or so ago.

    The problem crept up slowly, as in, I remember starting the car, driving off and 5 mins later thinking "Hey, is there something wrong with my AC?" at which point the AC came on (meaning it got cold) so I didn't think anything of it.

    Many thanks in advance for your kind assistance. :)

    Dia
     
    #1 Diotima, Sep 6, 2013
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It sounds like the system has a slight leak and the refrigerant charge is low. The pressure valve in the system is causing the compressor to turn on and off.

    The question is where the leak is coming from, and the answer to that will determine how costly the repair is.

    The compressor is probably OK if the car will cool down at least part of the time.
     
    #2 Patrick Wong, Sep 6, 2013
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  3. Diotima

    Diotima Junior Member

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    Thanks, Patrick!
     
    #3 Diotima, Sep 6, 2013
  4. Zedhomme

    Zedhomme Member

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    I really have no expertise in this area. There are a lot of brains and Prius unique parts to its A/C. I've attached a symptoms sheet, but you're probably going to have to take it to a dealer. I suggest one that deals with Prius because it is not typical of a lot of other A/C systems, being a compressor run by electricity from the HV battery, so it's not dependent on the gas engine running. It could just be one of the temperature sensors so it doesn't know how hot it is outside or inside and how hard it should work to get to the temperature you set.
    Found the DTCs for the A/C, so if you can get a diagnostic tool, you can at least check to see if it registered a DTC or not.
     

    Attached Files:

    #4 Zedhomme, Sep 6, 2013
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  5. Diotima

    Diotima Junior Member

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    Thanks, Zed. :)
     
    #5 Diotima, Sep 6, 2013
  6. Zedhomme

    Zedhomme Member

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    I don't know how far you are from Luscious Garage in San Francisco, but they have a great web site and reputation for fixing hybrids, especially Prius for a reasonable price. I'm in VA, but I emailed them a question one time about how much of the interior I had to take apart to get to the battery blower and they saved me a lot of time with their advice. They may have some info about your problem in their blogs.
     
    #6 Zedhomme, Sep 6, 2013
  7. nh7o

    nh7o Off grid since 1980

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    #7 nh7o, Sep 7, 2013
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  8. Zedhomme

    Zedhomme Member

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    In case you are asking yourself where the sight glass is, or what should I look for.
    Here is a diagram and info about how you should check it, i.e., A/C ON, All doors open, Set on MAX cool, Blower on HI. Also, what you can expect to see.
     

    Attached Files:

    #8 Zedhomme, Sep 7, 2013
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  9. Diotima

    Diotima Junior Member

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    Cool! I will check it out. Thank you both. :)
     
    #9 Diotima, Sep 7, 2013
  10. Britprius

    Britprius Senior Member

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    Diotima.
    It is common with front end collision damage for the two electric fans that draw air through the rads to be put back in the wrong positions as they counter rotate.
    I doubt this is your problem because of the time scale but it is easy to check. Turn on the AC in park and stand near the front of the car. If air can be felt blowing out of the front grill this is your problem. The fan blades will need to be taken of there motors and changed places leaving the motors where they are.

    John (Britprius)
     
    #10 Britprius, Sep 7, 2013
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  11. LEARNER

    LEARNER Junior Member

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    AC–43ACB1433Air Outlet Damper Position Sensor Circuit- Air outlet control servo motor (air outlet damper position sensor)- Wire harness between air outlet control servo motor and air conditioning amplifier- Air conditioning amplifier
     
    #11 LEARNER, Aug 21, 2020
  12. edthefox5

    edthefox5 Senior Member

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    7 year old post/
     
    #12 edthefox5, Aug 21, 2020
  13. LEARNER

    LEARNER Junior Member

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    Information for whoever is reading.
     
    #13 LEARNER, Aug 22, 2020
  14. ChapmanF

    ChapmanF Senior Member

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    Did something lead you to think that information about an outlet damper position sensor circuit would be of use to people reading a thread about AC fading in and out?
     
    #14 ChapmanF, Aug 22, 2020
  15. LEARNER

    LEARNER Junior Member

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    (y)
     
    #15 LEARNER, Aug 23, 2020
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