My 2001 1.6 Bravo will start making a rumbling noise (like a diesel) when I switch the air-conditioning on.

I recently had the air-conditioning serviced and the guy said it was not the compressor making the noise as when he turned the compressor clutch manually by hand it didn't make any noise.

Is it possible the Auxilary Belt Tensioner is making the noise when it's under the extra load of driving the air conditioning compressor too?

Could it be the cambelt tensioner?

Is there anything I can do to establish which component is making the noise?

Now i'm no expert on aircon infact i'm a bit of a muppet regarding it. lol

Working on logic... there are 2x belts. One cam belt and 1x aux belt.

If it was anything relating to a cambelt, the idler, tensioner then the noise would be constant.

If it was anything to do with the aux belt, alternator, tensioner, idler, aircon compressor pully wheel, waterpump, cant remember if on this engine it is cam or aux belt driven. Then again the noise should be constant.

The only thing that changes when you turn the aircon on is that the aircon clutch engages and rather than just the aircon pully wheel turning with the belt, the whole compressor internals turn. Therefore it sounds like this could be the cause of the noise.

The mechanic turning the pully would only be turning the outer pully not the compressor itself.

The only other possibility is that the extra load of the aircon is dragging on the tensioners.

Clive D said:

the guy said it was not the compressor making the noise as when he turned the compressor clutch manually by hand it didn't make any noise.

Click to expand...

i dont know why he assumes that turning it by hand will apply the same force, but i guess he failed physics at school.

use a piece of hosepipe to locate the noise. stick one end of the hose in your ear and point the other end close to suspected culprits while the noise is occuring. you can quickly tell the difference in noise even for parts that are close together. obviously be very careful not to catch the hose on a moving belt.

had a change of compressor yesterday. right after, at ard 2700rpm+ ( where the torque usually comes in ), it all felt lethargic with air-con on. and engine sounds like there's 2 engines, another one higher pitched, at this speed.
idle good. 850-920.

timing belt? aux belt? spark plug? ( injector indicator is off, tg )

air con does make your engine feel noticably flatter, it robs a lot of power from the engine. the high pitched noise is often a bearing, a seized or tight bearing will make the loss of power worse. again i would use the hose pipe method to locate the source of the noise. if the noise wasnt there before you fitted the compressor i would expect the compressor pulley bearing to be the most likely source, otherwise it could be any bearing on any pulley on either the aux or timing belt.

sweet.
thanks jahg