Intermittent A/C noise

[bigsikk]

My '06 M35X has a new noise - It's intermittent - Lasts about 7-9 seconds.

A/C will turn on fine, no noise - A/C is ice cold.

After about 10 minutes (give or take) there will be a low, pipe like noise / it sounds almost like if you were listening to an audio of a phone call and heard the phone ringing on the other line - It lasts about 7-9 seconds. Then goes off and about 5-8 minutes later will repeat.

If I reach up and cut the A/C during the noise it'll stop.

I've searched every way I know how for this cause, can't find it written about on here.

Thanks, in advance, for the assistance.

[steve_c]

Any work done in the engine bay that may have disturbed any A/C lines?
Sounds like you are transmitting a droning noise from an A/C line being in contact with a large metal surface, like the firewall or another line or component.
I have seen this more than a few times in the past, where normal A/C line noise is transmitted due to it chafing or rubbing against something else, (like the firewall, or another component or line) that then resonates to the cabin.
I would check the engine bay for an A/C line rubbing or touching another line or object, insulate it & see if the noise goes away.

Another possibility could be the metering device, (orifice tube or expansion valve) causing the chatter as the freon makes its way into the evaporator.
This could occur if your freon level drops a bit, and your ears might be picking up the change in the frequency at the metering valve as the freon makes its transition.
If that is the case, you have good ears! If the A/C blows cold, I would not mess with it.

[Davealan]

Hi having the same noise come on when running the A/C and idling in a parking lot over lunch time. Sounds like a bovine groaning but I am also experiencing intermittent A/C cut outs.

Is it a simple case of buying some canned A/C refrigerant and charging the 6 year old system?