I recently just installed a K&N CAI in my 07' FX4 and now whenever my AC or heater is running, im hearing a sound kinda like something is thumping every minute or two. Is it mabey a normal compressor sound that I'm hearing more prominently bc i know longer have the stock air box and tube? Or is this something I need to take in to get looked at? It only happens when the AC or heater is on...not just the fan. Thanks for the help.

okiranger

 

mine made the same sound with the old cold intake k&n

went to a diffrent unit and no more sound

 

That thumping is the ac turning on and off. When the ac compressor turns on it puts extra load on the engine so the IAC valve compensates for it.

 

 

The only increased noises a **open filter** (brand doesn't matter) will give are:

1) A deeper howel at heavy throttle.

2) A hissing sound at lower rpms. Mostly noticable at cold start.

Rich

 

I would agree but on rangers they do make some type of thump like the OP is talking about, its normal as far as I can tell. I have 97,000 miles on my truck and put an intake on at 30k miles, no issues yet.

 

zabeard described it best..."a thump" is exactly what it is...

 

I don't understand what it could possibly be. My K&N kit doesn't at all.

Does it do this when the motor torques to the side? Or when you put it in gear? Or is it just random (tempature related)?

Rich