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.
t440 ac not staying cold.
Discussion in 'Kenworth Forum' started by kenworth660, May 11, 2014.
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Dirty condenser maybe? Did you pull a good vacuum? Air in lines will screw with it
CondoCruiser Thanks this. -
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? -
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. -
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.
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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.
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