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air conditioner sighing

Discussion in 'Other Cars' started by Trollbait, Jul 17, 2024 at 3:00 PM.

  1. Trollbait

    Trollbait It's a D&D thing

    Joined:
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    I'm hearing a faint, intermittent hissing from the dash when the A/C is in use with the Outback. It reliably happens when the auto stop turns the engine off and on. Though it sometimes happens while cruising along. Don't know how long it has been going one. It's faint, and I regularly have the radio on. It was mostly luck I noticed it in the first place.

    The air out of the vent seems to take longer to reach cold than past cars. But there is more cabin to chill, the system is using a different refrigerant, and we are in a hot and humid wave right no, so this could be normal. The refrigerant meant I couldn't use the recharge widget I have to check the low side pressure.

    Is the sound normal, say from the compressor cycling on and off?
     
    #1 Trollbait, Jul 17, 2024 at 3:00 PM
  2. John321

    John321 Senior Member

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    I'll maybe give you a couple of things to think about.

    Get a temp gauge to stick in your vents to gauge how well the unit is dropping the temperature for you and what the delta (difference) is between the outside temp and the temp your a/c is putting out.

    A couple of years ago when we were having car A/C problems I bought a Halon gas detector from Harbor Freight to see if I could isolate a leak in the system- I couldn't.

    Your suggestion of measuring pressures is a tried-and-true method of determining the systems health.

    Eventually to isolate our systems problems we did have to revert to injecting dye into the system and let it eventually highlight the leak area.

    Car A/C's have TXV valves which regulate the pressure in the A/C systems and many times theses are located on the firewall near the evaporator core. These can amplify sounds when the refrigerant is changing states or pressures.

    The fact that your system is still working and cooling is encouraging and hopefully means there aren't any faulty components.
     
    #2 John321, Jul 17, 2024 at 4:52 PM
    Last edited: Jul 17, 2024 at 5:03 PM
    Trollbait likes this.
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