Engine is making humming noise - it increases when car accelerates. Stops when car reaches 40mph. Car shop says the noise is due to air conditioner compressor. (Brought car in for repair due to the noise - timing belt, water pump and belt were replaced. Noise remains - is louder now.)
Would the air conditioner compressor make such a noise? It doesn't matter if the air conditioner is on or off - it still makes the same nosie.

 

Doubt it. Hard to tell over the internet though

 

Thanks for your reply! Any idea(s) what could be causing the noise - it's a humming sound similar to what you hear from your radio when the station is not coming in (radio's working fine!).

 

I would really need to hear the noise, that description isn't something common

 

Mechanic at shop said it was a whistling sound if that helps.

 

Any chance you could take a video of it?

 

Will try to get a video to post. Right now my neighbor is using their trimmer/weed whacker. Sound from car sounds somewhat similar...... Thanks for your replies!

 

Went back to the shop again - advised the noise is the power steering pump - does that make sense? Car is now leaking oil.... (It was changed about one month ago. There are spots on driveway.)

 

It is rare for them to make noise without the fluid being low or aerated. It is common for the suction hose to leak or the reservoir to swell and leak, or break inside and aerate. It is also common for the suction hose to leak onto the alternator and cause it to make a noise.

 

Thanks for the reply! How much fluid does the power steering reservoir hold? I'll check the level tomorrow morning but something's leaking now..... The noise is when the car is idling and increases as you accelerate. Once you hit 40mph it stops. How serious is this? Expensive? I know the parts that were replaced were old but they weren't causing the noise. Thanks again!

 

I don't know how much just the reservoir holds, but I have replaces hundreds of reservoir/suction hose combos and one liter is always more than enough. Does the noise increase when you increase the RPMs even when the car is not moving?

 

Yes, it increases if you just rev up the car. What does that mean? THANKS AGAIN!

Just saw a power steering fluid that also stops leaks - any sense in buying that??

 

That means the noise is likely by something driven by the engine. It could still be the compressor, but I'm just speaking from experience. I might have replaced one or two compressors for noise. I've replaced dozens of alternators.

I would not recommend any band aid stop leak junk.

 

OK but please remember shop first said air conditioner compressor and then said it is power steering pump.. Checked power steering fluid this morning - it is very low. How big of a job is it to replace alternator?
As far as reving the car, the noise is there whether the air conditioner is on or off.

 

I don't think the shop really knows what they are doing.

Fill the reservoir and bleed the air out. Is the hose leaking? Is the reservoir leaking? Is the pump leaking?

Alternator replacement isn't hard. Takes me about 20 minutes but a first timer should expect at least an hour, maybe longer depending on mechanical ability.

 

Message says Try Slow Down or Shift Up. What the heck is happening???