Air Conditioning Problem ?

[woz]

In my ml today put air con on and the rev counter hunts up and down but stops when i switch air con off.
You can hear a loud noise as the engine ticks over on off on off,
Anybody any ideas.

Many thanks

[pointman]

i had the same exact issue.. everyone told me it was normal.

[woz]

but its very noisy, what do you think

[Nefum]

That more than likely is the AC compressor cycling on and off check and see if your system is properly charged. If that is not it have someone check your idle control valve. When a system has load on it ie air conditioning its suppose to kick up the rpms a little to stabilize system.