# 2 issues, hopefully some help



## Solion (Nov 25, 2017)

New Nissan user here. 

2005 Nissan Altima 2.5 

First issue, while in gear and stopped at say a stop light , I have vibration as if the idle is dipping too low (it may be?). It is not a missing cylinder sound, all the engine mounts are in good condition. I have checked the tensioner and the alternator. The vibration is a regular thrum and does not happen when the car is moving, Neutral or in park. Only when stopped and in gear. 


Second issue may not be an issue., But with the car set to vent only, no ac button or recycler lit. the compressor engages every 30 seconds. (it seems to exacerbate the first problem) Compressor only stops this 30 second cycle when blower/fan is turned off. 

I have already gone through the idle relearn without effect 

Thank you for your help


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## quadraria10 (Jul 6, 2010)

Does the AC button light work? Maybe its on but the small bulb is burnt?
I am not too sure what it is you are describing regarding your idle, but on my 2006 x trail with the same 2.5 engine, replacing the tensioner not only got rid of some belt noise but also pretty much eliminated all vibration when idling at stops. If yours is original, and more than 10 years old, changing it and the belt might just be the ticket.


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## theskater101388 (Mar 4, 2010)

If you have the fan set to defroster or defroster and feet I’m pretty sure the AC compressor will kick on and off to provide dry air for defrosting of windshield. Or atleast my ‘02 does that


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## BlownSkillet (Mar 6, 2018)

Sometimes, my idle drops way down, when the cooling fan comes on, but returns to normal soon after.


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## smj999smj (Jan 1, 2006)

A lot of Nissan engines idle a bit on the rough side. Raising the idle helps a little, but you need a capable scan or diagnostic tool to do it on these engines, IIRC.


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