AC freeze probe problem

Discussion in 'Trucks [ Eighteen Wheelers ]' started by jeffman164, Aug 20, 2022.

  1. jeffman164

    jeffman164 Medium Load Member

    559
    485
    Dec 4, 2012
    0
    1999 International 9200. Not getting power to the freeze probe. Question that I have is : Does the power come straight from the on/off switch to the freeze probe or is there any sensors before the freeze probe that is not letting power to the probe? Not too familiar with AC's .
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

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

  3. BoxCarKidd

    BoxCarKidd Road Train Member

    4,167
    5,981
    Aug 26, 2014
    0
    Freeze probe? Capillary tube in evaporator from thermostat?
    Best I remember the fan blower switch is a double switch with one lever operating both. One switch has an extra terminal. That feeds the the thermostat. Should be hot on low, medium and high.
     
    Rideandrepair Thanks this.
  4. Heavyd

    Heavyd Road Train Member

    7,625
    6,023
    Feb 4, 2009
    0
    The blue on/off switch triggers the "A/C Control" relay which sends power to the freeze switch. This power is from fuse F1-B usually.
     
  5. BoxCarKidd

    BoxCarKidd Road Train Member

    4,167
    5,981
    Aug 26, 2014
    0
    Thanks, Thought that was one later year models.
     
    Rideandrepair Thanks this.
  6. jeffman164

    jeffman164 Medium Load Member

    559
    485
    Dec 4, 2012
    0
    Ok. I will look at it in the next few days. Thanx !!
     
    Rideandrepair Thanks this.
  7. jeffman164

    jeffman164 Medium Load Member

    559
    485
    Dec 4, 2012
    0
    Getting power to the A.C. control relay and then when I turn the AC switch on , there is power to a second terminal on the A.C. control relay. which I would assume is going to the capillary tube thermostat. There is no power at the capillary tube thermostat what so ever. Is it wired directly from relay to Capillary tube thermostat or is there something else between ? Sounds like a broken wire somewhere.
     
    Rideandrepair Thanks this.
  8. Heavyd

    Heavyd Road Train Member

    7,625
    6,023
    Feb 4, 2009
    0
    Relay to capillary tube. If you use a jumper wire between that relay pin to 77H at the capillary tube, then power should be going through the tube and on to the compressor clutch.
     
    Rideandrepair Thanks this.
  9. jeffman164

    jeffman164 Medium Load Member

    559
    485
    Dec 4, 2012
    0
    I think that there was some jerry rigging with the electrical at some point. The A.C. works but the small condenser under seat ( I think that's what it is called) freezes up because no power to capillary tube. I am going to try the jumper wire from relay to capillary tube. Won't be until next weekend.
     
    Heavyd and Rideandrepair Thank this.
  10. jeffman164

    jeffman164 Medium Load Member

    559
    485
    Dec 4, 2012
    0
    I was wrong on my wording. I am not getting power to the thermostatic switch. I have checked the A.C. on / off switch and it is working.so there must be a broken wire somewhere. Question: Can I just add a wire from A.C. on / off switch straight to the thermostatic switch ? If yes, what size fuse should I add ?
     
  11. Heavyd

    Heavyd Road Train Member

    7,625
    6,023
    Feb 4, 2009
    0
    Not really. The power that goes to the freeze probe also goes to the low and high pressure switches. Locate your pressure safety switches on the outside of the cab under the floor under the heater box and see if they have power at one terminal when the ac switch is on. If they do, then your power wire from the relay is at least good to those switches. You can add another power wire to from the relay to the freeze probe as long as those pressure switches are also getting power when the ac is turned on.

    ***One important question I have forgot to ask is if you have an APADs module or not. This is a little electronic module that controls the ac and is mounted on the firewall near the coolant reservoir on the left side. Some of the wiring is different, but most to the freeze probe is the same.
     
    spsauerland Thanks this.
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

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