Intermittent AC Whistle or whine

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JDB5

Junior Member
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Location
Ga
Ram Year
2014
Engine
6.7 Cummis Standard Output
In my 2014 Ram 3500 Laramie I have an intermittent whine or whistle noise that is barely audible (wife says she can’t hear it) only when AC is on. It also occurs mostly or maybe only when I am in that sweet spot on the accelerator when there is little load or little deceleration (like cruising) but in all gears when it makes the noise. It has been doing it for 16 months. 4 months ago, AC felt like it wasn’t working well and then sometimes would work great. I did some checking behind the glove box and the recirculation door would hesitate and not close. I am in GA where it is hot 13 months out the year. I set both sides AC to 72 and leave it at AUTO. What I think I found is that the default setting for the recirculation damper is to open every time you shut off the engine and then it probably almost always closes when I start the engine to cool the truck. At that time, I helped the door close then unplugged the actuator, so it remains in always recirculate. The actuator is hell to get to. Since then, I am back to great AC and heat when needed. If it was an older vehicle, I would swear I had a leaky vacuum line as they would fluctuate under different accelerations, but I think my Ram is all electrical in the heater box. I am fearful it is the compressor and will lock and leave me stranded (I do carry an extra belt but not easy to change with that fan shroud). I have gone outside to listen under different RPMs but can’t hear anything wrong and I can’t seem to hear it inside the truck under different RPMs unless under load driving. Maybe a different blend door leaking but why at that 1500 to 1700 cruising RPM only? Thanks for any input.
 

Daw14

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Have you added a filter and filter door ? This year was not equipped with any, it became standard a few years later.

Reason asked is everything will be pretty dirty if never changed . That may be the cause of the whistle.
 
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JDB5

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No - I have often thought about it but never have added the inside air filter. I've had the truck since new and can see that one has not been put in and it looks easy to cut out if I want to.
 

Captain Freon

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I have a similar sound in my 2016 Chevy van that I use for work. It has a faulty pressure relief device on the ac compressor. It will sometimes release some refrigerant for no apparent reason. When the system is a tad low on refrigerant, it will whine off and on when it passes through the expansion valve. Just a thought.
 
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