2017 CX-5 Rattle noise at 1200-1400 RPM only when A/C running

[SweetPete]

All,

I've got a rattle-like noise at 1200-1400 RPM coming from the engine bay but only when the A/C is running. A/C itself is working fine. When the rattle can be heard, I can turn off the A/C and the rattle stops. Assuming it's A/C related, is the compressor going bad? Or is it belt slippage? Or something else? Thanks.

 

[HyFlyer]

I doubt the belt is slipping. How about pop the hood and stand there in front of the engine and see if you can notice where the rattle noise is coming from?

 

[yrwei52]

How many miles on your 2017 CX-5? My bet is the leaky and failing serpentine belt tensioner.

If the miles is up there, it’s time to replace serpentine belt tensioner, along with serpentine belt and water pump belt.

 

[SweetPete]

I'm just about to turn 70k miles. The belts, tensioner and water pump are all original.

 

[yrwei52]

I'm just about to turn 70k miles. The belts, tensioner and water pump are all original.

You want to open up the hood like HyFlyer suggested, check the belt tensioner, and start the engine and see if you can hear anything in the area. You may want to have a helper to raise the engine to 1200-1400 RPM with the A/C on and see if you can locate the source of the rattling noise.

At 70K miles If you see the wet tensioner then you should replace it along with new serpentine belt and water pump belt.

 

[SweetPete]

UPDATE: Replaced the belt tensioner and both belts. Noise gone!

 

[yrwei52]

UPDATE: Replaced the belt tensioner and both belts. Noise gone!

Thanks for the update.

If you have somebody did the job, can you tell us what is the cost for such job nowadays?

 

[SweetPete]

I did the job myself. Ordered the parts as a kit from RockAuto. Hardest part was removing the water pump belt - ended up just cutting it off. Accessing the tensioner from within the wheel wheel is a little tight and tricky. Make sure you have a long 17mm wrench for maximum torque.

 

[yrwei52]

I did the job myself. Ordered the parts as a kit from RockAuto. Hardest part was removing the water pump belt - ended up just cutting it off. Accessing the tensioner from within the wheel wheel is a little tight and tricky. Make sure you have a long 17mm wrench for maximum torque.

A kit from RockAuto? What brands included in the kit, INA? Gates?

Some had reported that the aftermarket water pump stretch belt is a bit shorter in length hence it’s very difficult to get it on.

 

[SweetPete]

All 3 parts were Gates. No problem getting the water belt on. The serpentine belt was a tad more difficult - I had to get the belt tensioner FULLY extended to get the belt on.