How do you prime a Carrier ComfortPro APU

Discussion in 'Trucks [ Eighteen Wheelers ]' started by 88 Alpha, Sep 1, 2015.

  1. KeithT1967

    KeithT1967 Road Train Member

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    We all have our moments. My last one cost me about $1000 when everything was totaled up.
     
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  3. WitchingHour

    WitchingHour Road Train Member

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    Forcing air into the tanks is something you don't want to do if you're not sure of what you're doing. There is a plug you can loosen, and I'd be better off to show you a photo than to try talking you through it. Also, if you do inject air into your fuel tank, you're going to want to undo the cap and relieve the pressure when all is said and done.
    Judging the truck being out of fuel based on whether or not the APU runs... the logic makes sense, but you don't really want to count on that. For one, not all the ComfortPro pickup and return lines are cut to equal length (the return tube is sometimes substantially shorter), and there are times when someone will have to disconnect the pickup and return tubes, forgets to mark which is which, then ends up installing it backwards... so you get an APU which doesn't run when you've still got plenty of fuel in your tanks.
     
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  4. 88 Alpha

    88 Alpha Trucker Forum STAFF Staff Member

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    @WitchingHour
    Thank you for your reply. Even though I was extremely low on fuel, I thought I had it calculated correctly so I would have 0.5 gallons of useable fuel remaining when I got to the fuel stop I wanted to get to. Yeah, I know that's not any room for the "what-ifs" but I know the area I was in very well, it's where I grew up. Flat terrain, small towns about 10 miles apart, all with 1 exit each, rarely a traffic jam, so the one -half gallon leeway was plenty, or so I thought. When the truck shut down, my initial thought was some kind of electrical issue because there was no spitting, sputtering, stalling, mis-firing, or hiccuping from the truck. It was just dead.

    Even though I don't want to run out of fuel again, I am interested in your first paragraph. The plug you can loosen and then undoing the cap to relieve pressure. You can certainly post a photo if you want to. This plug sounds like it might be something different than the bleeder screw. Also, when the shop got it going again, they took the fuel cap off, put their air hose into the opening, and placed a shop rag around the opening. I thought a shop rag would be too porous to keep air in the fuel tank, but it worked for them. I was in the truck, at the APU control box, ready to press the start button when told, so I didn't notice if he put some air in the tank, then quickly replaced the fuel cap or simply held the makeshift seal in place as I started the APU. I assumed he held the shop rag seal in place. Wouldn't this relieve any pressure in the tank once the APU was started and the shop rag seal removed? If he filled the fuel tank with air, then quickly replaced the fuel cap, it would certainly make sense why you would relieve the pressure before you were finished.

    The mechanic said I could do it myself with the hose that hooks up to the gladhand but it would take longer because the truck doesn't produce the volume of air that his shop did. He also cautioned me, if I were to do it myself, to be careful and be gentle on the trigger, as you can blow out a fuel line if you blast air into the tank.

    Again, this was a boneheaded thing to do and I don't intend to make the same error but perhaps another driver who does the same thing can learn the "how-to's" from this thread.
     
  5. WitchingHour

    WitchingHour Road Train Member

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    Sorry for the delay... I'm on vacation at the moment, and I kinda forgot... here's what I was talking about... IIRC, you can use either a 14mm or 9/16"
     

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  6. 88 Alpha

    88 Alpha Trucker Forum STAFF Staff Member

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    No worries about the delay.

    If the plug you are talking about is the nut/bolt combination at the 10 o'clock position from the oil fill cap, that's what I was calling the bleeder screw.
     
  7. WitchingHour

    WitchingHour Road Train Member

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    That's the one. I'm posting all of this from a phone, so I didn't get to give it the MS Paint treatment.
     
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  8. BJnobear

    BJnobear Heavy Load Member

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    Just had this happen to me. JCT told me the tap is just below where the red line on our Cascadias are at. Fill the right tank and crank it. It may take up to 15 tries holding down the start button, 15sec rest 60sec and repeat. If after 15 attempts, go to a TA. They did tell me this is a standard installation for most trucks, so your mileage may vary.
     
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  9. SaturnKnts

    SaturnKnts Bobtail Member

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    So i checked to see if my tank ran out of gas yesterday lol. And just thought I'd share how I got mine running.

    The system would crank and stop crank and stop and then crank limit reached after 5 or so cycles. I opened the bleeder valve and tried the air in the tank but never got fuel out of the bleeder. I had even taken the bleeder all the way out to check and make sure it was really fuel :)

    So looked at troubleshooting guide which really was no help.

    Started playing with the control inside the cab and held the apu on/off button down and it acted like a manual crank which I didn't see in the manual.

    Held it down 3 times for about 10 to 15 seconds each and I finally got positive fuel and start!!! Just thought I'd share my experience. Just need that extra cranking time the auto start does not give it.
     
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  10. BigHossVolvo

    BigHossVolvo Road Train Member

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    Thanks for sharing this!

    I recently had my Comfort Pro loose prime during a breakdown, and the dealer and TA could not get it going at all. Carrier told me to “just keep holding it till it goes” but all that did was overheat the starter. I did the 20 seconds cranking, rest 60 second (stop watch) and on the 8th try, the un-primable APU fired up and no issues!

    You definitely need the 60 second rest for every 20 second forced crank. I also think it gives the fuel time to settle, prob full of air bubbles.
     
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