W203 - air con hissing when on coldest setting

[cws196]

As above, noticed the air con making a hissing noise over the past month and it gradually seems to be getting louder. Seems to be coming from centre vents (above the radio) and goes immediately when you switch the fan off / goes gradually when you leave the fan running but switch off A/C.

Read about on here and some people suggest low gas, but some other people mention a loose vac pipe behind the light switch (which confuses me!).

I'll get it re-gassed soon, in the meantime, would a scan of the A/C module show up anything ie low gas (from a generic Snap-On reader > have a mate with access to a scanner)?

I've also tried the A/C reset by pressing both re-circ and demist buttons - it completes the self-test fine ie flashes for a time then stops flashing.

 

[Stratman]

A pound to a penny it's low gas

 

[grober]

Have a close look at the aircon condenser at the front of the car - 9 times out of ten that's where the leak is---- from road debris damage- may be obvious / may not.

 

[cws196]

I've had the car 6months and never had the A/C checkd/re-gassed, and the previous owner never had it done in 3years he had it either, plus no evidence on any of the receipts from MB dealers either - so the car may still be on the original gas.

Does the gas just naturally leak over a long period, or can it only be ever due to a leak?