APU Heat

Discussion in 'Prime' started by kidnya, Sep 17, 2013.

  1. kidnya

    kidnya Bobtail Member

    Mar 8, 2013
    Hey guys!

    It got pretty chilly in PA last night, turn the APU to heat, turned the temp up and got no heat....Is there something I'm missing?
  2. buzzarddriver

    buzzarddriver Road Train Member

    Feb 1, 2011
    Dallas, TX
    Well, depends on which brand of APU on the truck. And there is always the INSTRUCTION manual.
  3. kidnya

    kidnya Bobtail Member

    Mar 8, 2013
    Its a Thermo King TriPac and if I had the INSTRUCTION manual, I might not have to ask. :rolleyes:
    Chinatown Thanks this.
  4. Highway101

    Highway101 Road Train Member

    Sep 19, 2011
    Fallon, Nevada
    Can't speak for the ThermoKings, but are you sure your don't have a bunk heater under the bunk. I was told by the Shop that Prime mgt did not want them to have the bunk heaters run off the APU's but they install a separate bunk heater instead. I could be wrong, but every truck I drove had a separate bunk heater, as well as controls.
  5. cl8936

    cl8936 Light Load Member

    Apr 17, 2009
    St. Louis, MO
    Prime APU's don't have heat. The trucks have bunk heaters which are turned on by a knob located on the outside of the bunk.
  6. dannythetrucker

    dannythetrucker Road Train Member

    May 26, 2011
    everywhere, man
    I dunno about knob outside of bunk, but the first time I tried heating with an APU I had trouble and turns out I had a bag sitting right in front of the heater duct, that would promptly shut it off whenever it started up. Maybe you have the same problem ?
  7. Chucktaylor

    Chucktaylor Road Train Member

    Sep 26, 2012
    3 trucks, three thermo king apu, 3 bunk heaters.

    all 3 bunk heaters where controlled by the apu controller.

    Main power on, heat selected, apu on. I don't mess with fan as fan control has nothing to do with the bunk heater.

    Bunk heaters don't fire up to full blast heat on a dime, same with shutting down.

    Heat will come from vent under the bunk.
  8. jbee

    jbee Medium Load Member

    Jun 3, 2011
    APU's I've had were supplemented with oil fired Bunk Heaters such as Webastos, Espar etc. For example, on a Webastos unit, it may have a separate control which looks like a dial. The truck has to be off and not running in order for it to work.

    Lift up your bottom bunk and have a look. If you have a square looking box with ducting tubes coming out of it, that's part of the APU A/C unit. Look beside it. If there's another box, usually rectangular in shape, and a vent coming directly out of it and located on the under side of your bunk, that would be your bunk heater.

    You can also check the bunk area for separate heater controls. The images below may or may not be what you have, but no harm in checking. The one on the left is for an Espar bunk heater and the one on the right (The Dial) is the control unit for a Webastos bunk heater. Could be a digital control for newer units. It may be located just below the bunk as well.

    See if you have something similar and more help could be provided whether you have this or not. Just need to know more info.

    espar.jpg webastos.jpg
  9. kidnya

    kidnya Bobtail Member

    Mar 8, 2013
    Got it. It was the knob on the bunk and turn the apu off and heat is coming out a separate vent!! Thank you very much for your help!!
    dannythetrucker Thanks this.
  10. CondoCruiser

    CondoCruiser The Legend

    Apr 18, 2010
    Don't get impatient with the heat knob. It takes a good 5-10 minutes for the unit to warm up and the fan to kick on before you hear something. The same with the shutdown, the unit will blow until it cools down then it will shut off. You can go outside and look at the little heater exhaust pipe and it will puff smoke in the warm up stage. Then you know it's working.

    Thermo King Tripacs have the ability to add aftermarket heaters like Espar and Webasto are the big ones. Most are hooked up independently but might share duct work or the blower. It's up to the installer what route he wants to go as you have a few choices. Lift the bunk up and you'll see all the guts.

    Each one has their own website with how to use the different controls or how to find the trouble codes.
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