Got a different one for ya. A/C wont turn off.

  • #1

    Got a different one for ya. A/C wont turn off.

    It's the exact opposite of most people's problems. I got A/C working in my 88t and it blows ice cold out the vents during the hot summer months. Problem is, I got off work this morning, kinda chilly out, turn the digital HVAC to 90. Ice cold air coming out. I pop the hood, compressor is still engaged and spinning away. If I turn it off completely, the compressor disengages and I get hot air seeping through the vent as I drive.

    What's my issue? I'm leaning towards the temp sensors in the car not reading the right temperature. Can I check that in the HVAC diagnostics? If it comes down to frosted windshields before I fix this issue, I'll just unplug the ground running to the compressor.
    Some people never go crazy. What truly horrible lives they must lead.
  • #2
    I believe the A/C compressor runs when the heat is on to dry the air.

    Maybe it's also possible you have a leaking actuator diaphragm that's not opening the right vent door. I've had that too. I doubt that the in-vent thermistors are going bad, they're just passive resistors.

    I've heard however that the headunit can suffer the same electronic gremlins that plague other electronic components (dry caps/failed solder joints). I've been through 3 of them in my 84T. All with different failure modes.


    84 AE/Shiro #683/Shiro #820/84 Turbo
  • #3
    I went through and tested the diaphragms when I had the box out this summer. Unless it was between then and now (wouldn't be surprised), they aren't leaking.

    I do have a buddy with an 85T with digi gauges and can pull his unit and pop it in to see if it works. I'll check in to that.

    Some people never go crazy. What truly horrible lives they must lead.
  • #4
    The AC turns on when you run the defoster not the heat. There is a switch that kicks on when you have want the compressor to turn on. If you unit is a digital dash that is bulit into the automatic system so more than likely the advise you got to replace the unit is best bet. If you have analog there is a switch that might be bad.