Air con squaking when turning steering

[1643]

Sorry if it’s been asked before, I noticed that when my aircon is on and I’m turning the steering wheel it makes a squeaking noise. It seems silly as the two systems can’t possibly be linked together (or are they?) but I’ve been driving with air con on part of the day and off part of the day for the past month and it’s not a coincidence:

- air con off, turning - no noise
- air con on, driving straight - no noise
- air con on, turning - squaking noise

Any idea what could be the reason and is it safe? The car wasn’t doing that last year. Thanks in advance

[John Ratsey]

Are both the alternator and the aircon driven by the same belt? The electrical power uses significant power which would put extra load on the alternator which, combined with the aircon load, could cause the belt to slip.

[1643]

I’ve no idea of any belts I am not a mechanic, if that’s the case should I worry?

[embee]

I'm with John, sounds like the belt slipping when under too much load. Usually just needs tensioning, but if it's in poor condition it may need replacing. I don't know the detail of the belt type/run/tensioner etc on your car, I'm guessing it's not an auto tensioner pulley arrangement, more likely a swinging alternator, but that's a guess.

[culzean]

I'm with John, sounds like the belt slipping when under too much load. Usually just needs tensioning, but if it's in poor condition it may need replacing. I don't know the detail of the belt type/run/tensioner etc on your car, I'm guessing it's not an auto tensioner pulley arrangement, more likely a swinging alternator, but that's a guess.

The MK1 ( 2002 to 2008 ) is tensioned via the alternator pivot,  MK2 onwards have spring loaded tensioner pulley.

On the MK1 there is a slotted curved bracket on top of alternator with bolt that needs to be slackened,  and also the alternator pivot that needs slackening ( under the alternator - bit of a PITA to get to IIRC  ).

As John Ratsey says the electrical power steering takes 40amps + ( on MK2 it is 60 amps, which is why it is better ) - could be a new battery is needed because if the battery is failing and cannot help supply the current then the alternator will cop the full load,  the alternator pulley is the smallest on the belt so is normally affected most by any slackness. 

[1643]

Thanks for your help - I’ll ask the garage to look at it at my next service (in 2 weeks time) looks like it’s a simple fix for someone with knowhow

[degzi]

If you don't know the age of the belt just change it anyway. Mine failed at 135,000 miles 

It looked good but just decided to snap one day, I tensioned it a few months before as it was starting to slip quite allot.
Hard to tell condition of modern alternator belts as sometimes the rubber looks fine but the inner steel wires have had it.

Belt is no more than £15 - £20. So it's up to you how much for fitting.

[culzean]

Interesting article about drive belts,  Thank goodness the old V belts have disappeared - they were a PITA, IIRC they needed replacing every year or so.  The modern micro V serpentine type ( can flex back on itself like a snake ) are 1000% better,  I think the Honda ones use Kevlar tension fibres and possibly polyurethane or synthetic rubber for the belt.  Both side of the belt can drive ( one side is smooth ) but normally drives low power stuff of when a a large pulley with a big 'wrap' is available.         http://www.crankshift.com/drive-belt/


When I was working ( LOL ) we used micro V belts with steel tension members as both drive and electrical connections.  The belts ( they were not endless and were clamped each end, used in linear motion ) the steel cords ( about 20 ) went to connection blocks at each end and were used to carry power and signals from a stationary bit to a moving bit of equipment.

The big improvement on later Honda ( IIRC it started on 8th gen Civic and MK2 Jazz ) was automatic spring tension,  as the main cause of belts failing are incorrect tension.   

[embee]

Absolutely agree with Culzean, what is generally termed "poly-V" belts were a game changer for front-end auxiliary drives on engines.
You can get them with poly-V on both sides, though not that common, and as Culzean says, the smooth backside is generally used for the lower demand stuff, like cooling pumps. The limiting one is usually the alternator, small diameter means lots of flex angle which stresses the polymer a lot. The cords do all the heavy drive work. Big alternators with small pulleys usually have over-run bearings to allow them to spin on after the engine slows abruptly to avoid slippage, which destroys belts quickly. A high drive ratio alternator has a big effective inertia, running at maybe 4x engine speed.
A single serpentine run with an auto tensioner can save considerable cost in assembly and manufacture, plus it improves reliability and longevity, minimising costs.
There are "stretchy" poly-V belts now, for alternators etc, which don't need mechanical tensioning, but they are limited on power transmission  (belt tension has to be greater than drive tension force to avoid it coming "loose"). Essentially the proverbial rubber band.