Hey guys, I am having a problem here. When I start my truck, I hear a whining sound that gets worse with an increase in RPMs. Its loud enough to hear while driving down the highway... So I checked the belt/pulleys, and this is what I recorded... the pulley stops and starts every few seconds... is this supposed to happen? Would this be causing the noise that can be heard in the video? Also, I don't know if it's linked, but my A/C only gets real cold when I am driving (it doesn't cool the air when I am idling, and I live in FL so I am forced to shut off the A/C everytime I come to a stop!) is this linked? What does the pulley in the video do?

http://www.youtube.com/watch?v=5vCm_uNiw_Q

Thanks in advance!

 

sounds like a bad ac bearing. that pulley is the ac compressor pulley. its entirely possible, if not likely, the 2 situations are linked.

 

That is your A/C compressor. The compressor cycling could be a sign of too little refrigerant, although I've heard them cycle faster than that. I'd think the whir should change with the loading of the compressor bearing. Look and listen to the idlers and the tensioner.

 

The fact that your AC is not cold when you stop is a sure sign that your condenser fan is not working. Check the small "radiator" and fan on the drivers side, that fan should always be on when the AC is turned on. If the fan isn't turning, it's not cooling the refrigerant and the AC condenser is kicking off due to excessive heat / pressure. When you are driving there is enough natural airflow thru the condenser to properly cool the system. Rockauto.com has just the fan motor for around 80 bucks and if you search youtube for 1aauto repair videos they show how to do it. And there's threads on here about it, I did a write up as well with pics.

I'm not sure about that noise. It might be the AC pulley, but it could also be a simple to fix idler pulley. what year is your truck and how many miles?

* oh if the fan isn't spinning, first check that there is 12 volts at the connector for the motor, just in case it's a wiring / fuse or relay problem instead. Sometimes smacking the fan housing with a small hammer will get it to spin for a bit (the less accurate, non technical way to check for power LOL I don't know how or why that works but I've heard about it many times and I've watched my mechanic do it when he diagnosed my AC problems, which was the fan motor.)

 

Thanks guys. The fact that it is the A/C pulley makes a lot of sense. I do not notice the noise going away when the pulley engages, though (its a constant noise, and high RPMs makes it louder)... The truck is an 2005 ram 1500 with 90k miles (and the belt has never been replaced, I know, I need to do that!)

So it could be just the fan? What if that fan is spinning like it's supposed to? Does that mean it could be the condenser itself? Should I just try to add refridgerant like someone suggested?

Also, I am not too familiar with what pulleys are which (tensioner/idler/etc)... is there a diagram that can point these out?

I will check out the fan later and report back, thanks for the tips guys!

 

Check out this thread to download the service manual for your truck. It will have every little bit of info you'd ever need.
https://dodgeforum.com/forum/3rd-gen...-download.html
oh, what size engine do you also have. If you have the owners manual there is a engine diagram in there. The idler pulley is basically just a free wheeling pulley to allow the belt to properly route. There are pulleys on the alternator, engine crank case, power steering pump, AC compressor; then there is the tension adjuster puller (this is the one attached to a big spring assembly), and usually just 1 more pulley that just bolts to the engine. Take the drive belt off and see if there is any wobble or wiggle in any of the pulleys (I haven't had much luck doing that, even tho the idler pulley fell apart shortly after I checked).
I'm thinking your refrigerant is not low - symptoms of that are good cooling only for first 30-40 minutes, then it warms up, if it's really low it won't cool at all, and from what I heard Dodge's do not have a low pressure cut off sensor to protect the system when it's too low.

 

I have a 3.7L v6, I will check out the service manual

So, how do I take the belt off myself? Do these have the spring loaded tensioner that I turn to loosen the belt, or do I need some kind of removal tool?

And I do believe my refridgerant level is fine, it gets ice cold while I am driving

Thanks for your help

 

Thought I'd update, even though it's been a while lol!

Idler tensioner pulley was bad, bad ball bearings. Replaced, noise went away