AC question

Discussion in 'Trucks [ Eighteen Wheelers ]' started by skman, May 11, 2026 at 10:00 AM.

  1. skman

    skman Medium Load Member

    314
    133
    Aug 26, 2013
    Saskatchewan
    0
    2016 Pete 389 w ISX15 2250

    Can anyone tell me why a AC compressor clutch will kick on but never shut off?

    System is showing 80psi on low side and it never drops and doesn't cool at all. Fan never kicks in (unless I unplug the AC switch) and when I kick the fan on....low side pressure still doesn't move. The low side line isn't cold to touch towards the compressor like they usually get...and the hot side lines didn't seem to be getting hot either.
    Not sure what high side is doing pressure wise because I didn't have my gauge set with me and was using cans.
    Added one can and compressor clutch kicked in. Added 2 more and realized pressure wasn't moving and fan hadn't kicked in... so didn't add the last can.
    Not sure where to begin with this.
     
    Last edited: May 11, 2026 at 10:06 AM
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. bad-luck

    bad-luck Road Train Member

    3,458
    6,381
    Nov 16, 2013
    Baltimore, Maryland
    0
    May be low on freon. The only sure way to know, is to drain the system and put in the proper amount.
     
    skman Thanks this.
  4. wore out

    wore out Numbered Classic

    17,503
    218,578
    Jun 5, 2013
    CHASIN THE DEVIL'S HERD
    0
    Easy your compressor is shot internally it’s not pumping.
     
  5. Deezl Smoke

    Deezl Smoke Medium Load Member

    546
    359
    Feb 12, 2011
    Hillsboro Oregon
    0
    Could very well be shot, or in the process of catastrophic failure. A small particle may have entered the system and is plugging the expansion valve(s).

    The fact that the compressor runs means the pressure switches are closing the circuit. So refrigerant level is likely not an issue, or much of one. But the refrigerant is not circulating. So either pump not pumping, or system has an obstruction, likely in the super small orifice of the expansion valve(s). IMO.
     
  6. wore out

    wore out Numbered Classic

    17,503
    218,578
    Jun 5, 2013
    CHASIN THE DEVIL'S HERD
    0
    If the system had an obstruction with a functioning compressor the low side which is suction would pull itself into a vacuum. The high side would also most likely hit the high pressure limit switch and kick the compressor out or blow a hose
     
    Deezl Smoke and 062 Thank this.
  7. Deezl Smoke

    Deezl Smoke Medium Load Member

    546
    359
    Feb 12, 2011
    Hillsboro Oregon
    0
    Here's an old thread of mine from right at 1 year ago.
    What is in my AC line at the expansion valve? Updated.

    Sleepers do have their own expansion valve I learned. Which was a duh moment for me. The sleeper has it's own temp control, so how could it not have it's own expansion valve. :oops:o_O
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.