AC now blowing hot

Discussion in 'Trucks [ Eighteen Wheelers ]' started by EWV, Aug 24, 2016.

  1. EWV

    EWV Light Load Member

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    Mar 22, 2016
    0
    Hi sorry if this has been posted previously.

    Kenworth w900l 2006
    Ac / heater all been working great.
    Freon level dipped a while ago so topped up with a canister until I could get into a shop....worked perfect.

    2 or 3 days a go the ac was blowing and the whole fan in the front momentally stopped and resumed almost instantly (turned out a loose connection on the on off dial which then melted the connector and switch...problem caught very early no apparent damage to wiring and both replaced...all seems ok).

    Booked in today for a AC system check and recharge.....the ac had started to blow not so cold air again.
    They did the system said it was all in good working order and put a fair amount of freon in saying it was fairly low.

    Took truck out of workshop it only blows hot air. Mechanic scratched his head and said hmmm.

    Had to get to an unload so had to leave but the guy said the only thing he could think of was taking the entire dash out to get to the fins / flaps.

    Just wondered if anyone had any other ideas or suggestions ....or if it is as he said then what am.I looking for behind the dash???

    Don't think the condenser unit is the problem as it was fine until the system was recharged and the bunk ac has continued to blow cold through out all this.

    Thanks in advance, lady trucker
     
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  3. WitchingHour

    WitchingHour Road Train Member

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    Broomfield, CO
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    There should be lines coming out of the engine block on the right side, and there should be valves on those lines... one valve goes to the heater core under the dash, one goes to the heater core under the bunk... close the one off which goes to the heater core under the dash (you can figure out which is which simply by looking at where the lines go to). Cut off the coolant to the heater core under the dash. If your AC gets cold after that point, take a look on the right side of the engine compartment, by the firewall.... you'll see the hose going to that heater core. There should be a device encase in plastic, with three coolant hoses running through it (including the one going to the heater core), and an electrical connector. That's the heater control valve, and it's not uncommon for those to take a dump.
     
    D.Tibbitt, EWV and pbrstreetgang Thank this.
  4. EWV

    EWV Light Load Member

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    Mar 22, 2016
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    Sorry delay...thanks yep it was that valve...quick easy fix thankfully. Thanks for your help
     
    D.Tibbitt Thanks this.
  5. Mellodrama187

    Mellodrama187 Bobtail Member

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    Jun 23, 2019
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    Air conditioning system blowing out hot air when running my 2011 freight liner cascadia. Please tell me why this is happening or what I can do to fix it
     
  6. D.Tibbitt

    D.Tibbitt Road Train Member

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    Gettin' down westbound
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    Funny how when a mechanic scratches his head he instsntly comes up with the most expensive thing he can do that isnt going to fix the problem. Makes u think about their thought process
     
  7. boneebone

    boneebone Road Train Member

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    Mar 13, 2009
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    Without actually being there to look at your truck it could be a number of things, you may have a freon leak somewhere, failed A/C compressor, blown fuse for the HVAC system, blend door motor not working, faulty high pressure switch, clogged orifice tube or expansion valve.
     
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