AC Compressor Not Turning On

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Haplo888, May 15, 2019.

  1. Haplo888

    Haplo888 New Member

    May 13, 2019
    2008 Prius
    I got some pure R134a refrigerant (no oil) and a hose with a gauge to try to fill our 2008 gen2 prius. It is blowing warm.

    But when I connected the gauge it shot up to 90psi (L side) and never dropped, making me think the compressor is not turning on. The same gauge does go up and down on another car.

    A mechanic mentioned the compressor might not turn on at all if it is too low on coolant. But I am a bit apprehensive about adding coolant when the psi is so high.

    Is there much risk in adding some coolant to see if I can get the compressor to come on?
  2. exstudent

    exstudent Senior Member

    Jul 11, 2009
    Torrance, CA
    2007 Prius

    You don't know what you are doing.
    • What about the high pressure side? (Whats that you ask?)
    • What about the manifold gauges?
    • What about leaks?
    • Did you know the AC system is a closed system? (What does that mean?) A closed system by definition is closed: nothing in or out. However, in the real world, the automotive AC system can loose small amounts of refrigerant over time due to leaks (via seals), or massive amounts of refrigerant due to equipment failure or vehicle accident(s).
    • You may have introduced contaminants by
      Unless the other car was a Toyota/Lexus hybrid.
    • For perspective, I have not had to add any refrigerant so far! 2019-2007 = 12years. Obviously NO leaks. No front end accident.

    Avoid this mechanic. Doesn't know about AC systems either. Comical though. Ask him where does one add coolant for the AC system, and where does one buy this AC coolant.

    Good luck finding a competent AC person who knows how to diagnose and repair hybrid AC systems. Too many shops don't know how to work on AC systems in general, especially, let alone the Prius AC. At the very least, a knowledgeable shop will have a hybrid manifold gauge, and non-hybrid manifold gauge.
    #2 exstudent, May 15, 2019
    Last edited: May 15, 2019