t440 ac not staying cold.

Discussion in 'Kenworth Forum' started by kenworth660, May 11, 2014.

  1. kenworth660

    kenworth660 Bobtail Member

    1
    0
    May 11, 2014
    0
    Ok I have a 2012 t440 that wouldn't blow cold ac I replaced the compressor, drier, expansion valve, checked my blendoor, blew my lines and drained all 134 and put new in and is kicking in and out fine. When at an idle it blows cold ! When I get moving it starts to blow warmer and warmer. Am I missing something ? Please help thanks.
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

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

  3. Helowrenchturn2

    Helowrenchturn2 Medium Load Member

    484
    139
    Apr 23, 2013
    0
    Dirty condenser maybe? Did you pull a good vacuum? Air in lines will screw with it
     
    CondoCruiser Thanks this.
  4. CondoCruiser

    CondoCruiser The Legend

    19,726
    18,731
    Apr 18, 2010
    Tennessee
    0
    Are you sure you have enough refrigerant? You can have enough where the low pressure switch works at idle. Then at higher rpms the refrigerant flies through the system and doesn't support the designed system pressure and the compressor kicks off again. .

    Double check your pressures if you have gauges. You might need another 4-8 oz or so.

    Did you pull a vacuum after working on it?
     
  5. snowwy

    snowwy Road Train Member

    19,720
    12,268
    Jul 6, 2009
    0
    yep, always pull a vacuum. and if you can, run the fan switch.

    i pump mine up to 140 on the high, which runs around 25 on the low. i also rev the motor up too about 1400 using the cruise. with fan on.

    revving the motor does 2 things. you can fill the system 5 times faster then at idle. and you know what your pressure is more likely to do while your driving down the road. which is 90% of your running time. (typically speaking).

    chargine at an idle will take forever to charge. and you won't know the real pressure as your driving down the road.

    getting cold at idle is easy. also, pay attention to the receiver dryer. mine always freeze meaning a full proper charge. getting it to just sweat only means your close. and won't blow quite as cold.

    i get 35 - 40 degrees out the vents.
     
  6. snowwy

    snowwy Road Train Member

    19,720
    12,268
    Jul 6, 2009
    0
    i hate mechanics who can't get anything cooler then 55 and say it's working just fine. and the receiver dryer isn't even sweating.
     
  7. KWmech

    KWmech Light Load Member

    141
    40
    Jun 16, 2012
    0
    Sounds like you have a problem with your heater control valve letting a little hot coolant through. At an idle the a/c will cool fine since not much is getting by but going down the road the pressure increases and more hot coolant flows through.
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

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