air con pump replacment?

[martthefart]

Hi all,

Question to the class. My K reg 124 300D auto with 154K miles has started to make some strange noises. The noise can best be described as like a loose nut or a spanner in a tin can. At first i suspected engine mountings as I think these are the original ones, but my non specialist tech (who are very good) says on investigation its not the engine mounts. They had a big pry bar to take the engine weight which had no effect. They say the noise appears to be coming from the air con pump and suggest the pulley or AC pump bearing may have failed. I definitely agree that the noise is coming from the right hand corner (looking at the car) where the pump is located. The noise appears to disappear when the engine is throttled (about 700 revs does the trick) and it seems to change the noise when going up inclines like speed humps. It now also seems more pronounced when engaging Drive, though initially engaging reverse made more noise than Drive. An incline definitely seems to have an effect. I have yet to take off the serpentine belt to see if this affects the noise heard. Now for my question:

1) is it likely to be the engine mount, if so why would would the rattle appear to be coming from the lower right corner of the engine block?

2) Does it sound like the air con pump bearing has gone, if so can it the bearing itself be replaced or does it mean new/recon pump and regas job? Where's the cheapest to place to source the part?

3) Could it be anything else or even a combination of 1) and 2) above.

Thanks in anticipation of your expert comments.

Mart

 

[Sprint'n'Go]

I recently had an A/C leak on the wife car. before the pressure fell enough to disable the system the compressor got very noisy and rattley. I feared the worse and suspected the compressor but when the repair was done(a leaky condensor) the repairer told me that the compressors often do get noisy when the refridgerant pressure/volume drops.

Maybe it's time for an A/C regas as this should be done every couple of years and should cost about £60-90 depending where you go and providing your system is using the current refridgerant as some older systems require work to convert to non CFC gas.

 

[martthefart]

condensor

Whoaah. Is the condensor the expensive repair that takes about 12 hours of dismantling the dash or can a leak be fixed by other means?

 

[Sprint'n'Go]

Whoaah. Is the condensor the expensive repair that takes about 12 hours of dismantling the dash or can a leak be fixed by other means?

Calm down Mart. The condensor fault on my car was coincidental to the rattling pump. All cars naturally lose the refridgerant slowly over several years. If you haven't had the aircon regassed for a few years then this MAY be your problem. The expensive dash out job you are thinking of is the evaporator(the bit that gets cold). The condensor(the bit that gets hot) usually sits in front of the radiator and is prone to stone punctures or in my case rotting due to trapped leaves etc.

The aircon guy you use should do a deep vacuum pressure test before regassing to ensure there are no leaks in the system(a constant pressure maintained over perhaps 15 mins indicates a clean bill of health).

As I said previously the rattle could be your compressor that is running low on gas or it could be knackered? Who knows. As you say you haven't definitely pinned down the source of the noise it could be something totaly unrelated.

In My case (on a vauxhaul astra) turning the air con off stopped the noise as this disengaged the compressor clutch. Your car may be different.

 

[martthefart]

Air con

Thanks Sprint 'n Go.

I knew there was an expensive ac job requiring the dash being removed. I tried switching the air con off, but the serpentine belt still rotates the pulley on the front of the unit. I will remove the belt one day and see if the pulley makes a rattle as it rotates or if the noise is from engine components other than any of the pulleys on the front of the engine block. The air con does seem to work fine, cools the car down quick and blows ice cold, so who knows. Thanks for the comments anyway, certainly gives food for thought.

Mart

 

[Sprint'n'Go]

Mart,

Your mention of serpentine belts has jogged the old grey cells and I seem to think there has been a lot of mentions about the belt tensioner developing a rattle(I think the tensioner unit contains a damper that can fail?). Try searching the forum for belt tensioner problems and see if that is any help.

 

[martthefart]

Yep. There is a serpentine belt dampening shock on the front of the engine. I had this replaced last year and judging where the sound comes from i don't think its this. Thanks anyway mate.

Mart

 

[steve kane]

Does anyone know if its possible to overhaul an Air Con Compressor yourself?
steve.