Sound from underhood when AC on

[snoopy123]

When I turn on AC, the air is cool, but there is a sound from underhood. I am not sure whether it is the sound from compressor. Please give some advice. Thank you.

[mazdatech]

Sounds like you solved it yourself....when you turnon the a/c it makes a sound right so I am guessing if you turn it off right away the sound also goes away.........you have answered your question.

[snoopy123]

what might cause this sound? Need oil to lubricate? Thank you.

[Wa jang chang]

You suppose to hear some sort of noise from the compressor motor being engaged when you turn the ac on. If the sound is something new, you may want to inspect the a/c driving belt for its condition. It might be worned out, requiring replacement.

[snoopy123]

Originally Posted by Wa jang chang

You suppose to hear some sort of noise from the compressor motor being engaged when you turn the ac on. If the sound is something new, you may want to inspect the a/c driving belt for its condition. It might be worned out, requiring replacement.

The sound is out only when AC turned on. When AC is off, then no sound. Is ac belt same as compressor belt? Is the ac belt running only when ac on? Thank you.

[Wa jang chang]

Originally Posted by snoopy123

The sound is out only when AC turned on. When AC is off, then no sound. Is ac belt same as compressor belt? Is the ac belt running only when ac on? Thank you.

You meant to say The sound is on only when AC turned on, right? When you press the ac button on the instrument panel, it actually energizes ac relay to engage the ac compressor motor (magnetic clutch). Elentras (at least 2001 model) use three drive belts to run accessories such as ac, alternator, and power steering/water pump. When ac is off, the ac belt is running free-wheeling (no load) and when ac is on, the magnetic clutch gets engaged and ac drive belt is now running the compressor motor. Yes, AC belt is compressor motor belt. Yes, the AC belt runs when engine is running, however, the AC compressor motor does not run until you press the AC On button. While engine is running, have someone turn ac on and off. You should be able to see and hear the AC compressor motor engaging/disenaging. Based on what you described here, I think the noise is coming from the ac compressor motor. If you have not enough freon (now they call something else), the motor works intermittently (i.e. engaged and disengaged by itself), which gives out constant clicking noise. You have not really described what this noise is like....