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AC not working - doesn't appear to switch on

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Robalov, Jul 25, 2020.

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  1. Robalov

    Robalov New Member

    Joined:
    Jul 25, 2020
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    Location:
    Portland, OR
    Vehicle:
    2005 Prius
    Model:
    III
    Hello all,

    I'm having some trouble with my AC and I'm rather new to owning a Prius, so I'm looking for a little guidance here.

    My AC doesn't appear to turn on, so the fans only blow ambient temperature in the vehicle.

    I've checked my codes and I get 42, 72, 74. I had searched and didn't see someone with this combination (I may be mistaken however.)

    I've checked what I could with the Torque app and when toggling the AC on and off (and varying target temp from high to low) on the MFD, nothing on the Torque app watch variables change.

    Variables:

    Aircon Req - always reads no

    AC power - always zero

    AC gate - always open

    Since I'm unfamiliar, I don't know if these are supposed to toggle (seems reasonable to assume they should), and secondly, what is 'AC gate'?

    Given these faults, and the google 'research' I've done, I'm focusing my attention to the electrical side of the AC unit.
    All the fuses/fuse array look good, are there any relays I should check?
    Possible failure of the AC amplifier likely?

    Cheers for any insight / experience on the matter.

    /Rob

    For reference - manual diagnosis for the codes above.

    42-
    - Air inlet control servo motor
    - Wire harness between air inlet control servo motor and air conditioning amplifier
    - Air conditioning amplifier

    72-
    - Hybrid control ECU
    - Electric inverter compressor (w/ motor compressor)
    - A/C inverter (inverter with converter)

    74-

    didn't see error 74 listed
     
    #1 Robalov, Jul 25, 2020
  2. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
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    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Most of the time the compressor won’t turn on if its low on refrigerant. This is determined via a pressure switch. However I would not just recharge it with a can of r134a, instead it should be recovered and then weighed in because of the variable capacity compressor. Best thing to do is to find an auto ac shop with Prius experience.
     
    #2 rjparker, Jul 26, 2020
    Raytheeagle and lech auto air conditionin like this.
  3. ChapmanF

    ChapmanF Senior Member

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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    H᠎i, when you say "manual diagnosis", does that mean you referred to the repair manual to look those up? If you did, there should be a whole section of troubleshooting workup information right where you found each code, which should help.

    I would say the 42 is not your first order of business. You might easily be able to confirm that the air inlet door isn't moving properly (you can see it if you take out the glove box, as if you were going to change the cabin filter). But that can be a project for another day. after the A/C mystery is solved.

    I would gravitate to the workup steps for the 72, for starters.
     
    #3 ChapmanF, Jul 26, 2020
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