Rattling noise from A/C

[jackconcord]

My A/C has stopped blowing cold air. The fans seem to be working OK, but only blow warm air. Also, when I switch on the A/C button, I get a rattling sound from under the bonnet, which disappears when I switch off the A/c.
I'm wondering whether the system just needs re-charging (could the lack of fluid cause the rattle?), or whether it might be a sign of something more serious - such as a faulty compressor?
Any opinions would be gratefully received.

[mike020150]

Without hearing the car's sad noises and examining it, there isn't too much advice that can be given except to suggest a visit to an aircon agent. Although aircon systems lose a small quantity of gas over time (usually noticeable by the aircon fans steadily working harder to or failing to maintain a low temp setting) any serious loss of gas means there is a hole in the system (typically a stone through the condenser at the front of the car or seal/bearing failure of the compressor). Mike.

[jackconcord]

Thanks Mike. I decided to just take the car into Kwikfit yesterday to get the aircon recharged (£49) which seems to have done the trick, as it's blowing cold air now & the rattle has disappeared. However, the technician said there was hardly any pressure left in the system at the start of the process - so time will tell if there's a leak or hole, as you suggest might be the case. Jack

[oldtimer]

Pleased to hear the noise has gone.

Just a thought while we are on the subject.

Many moons ago it was common practice to vent the gas to atmosphere by attaching a piece of rubber tube to the appropriate outlet and the other end into a milk bottle- don't even have milk bottles any more - the gas vented off but the oil remained in the bottle. The amount of oil gathered was measured and replaced into the system with new.

A specific amount of oil is introduced into the Air Con system during manufacture. During normal operations the oil is randomly transmitted around the system. I have a chart somewhere that tells you to allow so many CC of oil to for each component replaced ensuring that the correct quantity of oil is retained.

Where is this all leading you may ask!
I have never used or watched being used, the modern Air Con charging rig.
What I do know is, that oil in the system is critical for the lubrication of the pump.
In my experience a gas loss is invariably accompanied with an oil leak

Although you mentioned that the system has been satisfactorily recharged you make no reference to replenishment of oil.

I would ask you to give this some consideration as I would not like you to suffer compressor failure in the future.

Perhaps other members would care to comment on this aspect

Oldtimer

[jackconcord]

That's interesting, Oldtimer. I don't think the process Kwikfit use involves topping up the oil content. I was trying to keep an eye on what was involved, but it all seemed to be done automatically with little manual activity. I'll obviously need to keep an eye on the aircon performance, & if the problem returns, then I'll obviously need to consult a specialist.