1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

1990 Hijet Air Conditioning

Discussion in 'Daihatsu Hi jet' started by Ebogen, Jul 14, 2022.

  1. Ebogen

    Ebogen New Member


    I was browsing other posts and could not find any with an answer to my question so im posting it her hoping someone might have an idea where to start.

    I have a 1990 Daihatsu Hijet S83p with Air Conditioning. When i got it last year it was cool outside and i never tested AC. I attempted this summer and it did not work. I did not look into it much at that time and just recently started looking at it but do not know what really to look for. But basically nothing happens when you turn the cooler box inside to the coldest setting, the AC compressor does not come on, and no cold air.

    Things i did so far. Disconnected the wire going to the AC Compressor front and reconnected it, took out the cooler fuse and relay right next to it to make sure they were good. Reached behind the cooler box in the center of the cab and disconnected the wire and re-connected it and checked for voltage (got no voltage) . I do not have a gauge to check the refrigerant PSI , however i did just quick press the pin to make sure something was there and did get a hiss for a second.

    What I am confused about is that it appears that the body of the Hijet is not ground. When i test from the battery positive to the screw terminal on the front of the AC compressor it is at 12-14volts however i would expect the body to be ground and the screw terminal to be hot to turn on / off the compressor. Then also when i touch the positive battery to anywhere else on the engine i also get voltage. So i am confused it appears to be positive ground. I would have expected that the screw terminal on the front was the way that the magnet clutch engaged by energizing, but with it always being positive even when all the fan and air con is off, i have second guessed myself.

    I was wondering what to check for next. Maybe someone has some ideas for me.

    As always, thanks for your time and i look forward to reading the replies.

    Attached Files:

  2. shogun

    shogun Active Member

    First thing to check is if there is enough refrigerant in the system, there are usually 2 limit switches, 1 for too high, 1 for too low, if they switch off, the AC compressor will not start. Your car's air conditioning system has two switches that protect the compressor and the refrigeration circuit. The pressure switch turns the system off when the pressure is too low/high to prevent damage to the compressor.
    Nautydog1 likes this.
  3. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    It might be a ground controlled circuit, like the lights are.
  4. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    Sorry I can’t be more help. Guessing that the refrigerant has leaked down, and the pressure low pressure switch is keeping it from kicking in. You might want to try adding some refrigerant and see what happens.
  5. Hegels

    Hegels New Member

    Hi, I have a 91 jumbo with AC. It runs so I know all the circuitry works even if it doesn't get super cold (i think its just low on refrigerant). If you want me to make any measurements to compare to yours please let me know.
  6. streetweapn

    streetweapn New Member

    I use a normal test light so try to follow, first hook the clip of the test light to the positive battery, it should light when you touch the tip or pointy part to the negative post on the battery or any place on the motor block or the a/c compressor housing showing a normal condition. now hook the test light clip to the negative side of the battery and touch the positive with pointy, test light will light. you just checked your test light and are ready to use your test light to see if you have power to your a/c compressor clutch wire. Unplug and test the wire at the harness side of the compressor, if you are getting incoming power and the clutch is not engaging then either the plug or the clutch are bad maybe. If you get a lit test light at the ground screw on the a/c compressor with the test light clip on the negative side of the battery then you have a ground problem. Now you can use the test light to check your over or under pressure switch, you should get a lit test light on both wires if you use a needle to probe the wires with connector still plugged in and the switches turned on
  7. thedakotakid

    thedakotakid New Member Supporting Member

    Did you ever get your air sorted out? Thanks for the legwork you did on your truck. I followed your path.

    Does anyone have a good AC wiring schematic?

    Notes so far:
    The switch at the back of the heater controls that connects when you choose recirculation appears to be working, but I could not find/feel a wire back there. I am guessing this energizes the AC unit on the floor
    No power going to the bottom AC unit (based on wires on the back of the unit)
    One hot wire (I think it was yellow with green stripes) coming off the bottom AC unit)
    The COOLER 10a fuse is there, not blown
    The wire going to the AC compressor clutch is negative. The grounding screw on the compressor is negative. This seems a bit off.

    How can I jump the clutch to see if it will lock up (Click, click, click)
    Is there a relay behind the COOLER fuse?
    How can I jump the safety switch for low pressure (Just to test)

    Any ideas are more than welcome
  8. 4x4prepper

    4x4prepper New Member

    > The wire going to the AC compressor clutch is negative.

    How some relays work is there is a single wire going out, the lever inside the relay touches ground inside the relay. When you hit the relay with (+) from a switch, the arm moves from it's resting (-) and connects the wire going out to the (+) input. Remove the (+) and the magnetic field collapses, the tiny springs move the bridging lever back to (-).

    The thing to check is continuity from the switch connector on the compressor to the relay connector with the battery disconnected.
    thedakotakid likes this.

Share This Page