hissing noise when using air-con

[Dirtyharry]

over the past couple of weeks, I have been hearing a hissing noise coming from the main dash vent when using the air-condition.

it doesn't always happen and the air is still fairly cold.

is this a sign that the gas needs topping up ?

 

[television]

It would not be a gassing thing as you cant hear that, but could be air from a vent control,,what is the car

 

[DougCLK320]

Hi Malcolm, good to have you back on the forum.
When my CLK was nearly out of gas, the A/C was working cool-ish but I got an occasional "hissing" from deep behind the dash. Since regassing (£45 from KwikFit) it's super-cold and hasn't hissed since. Correct level is (I think I remember) 780g of refrigerant and I was down to only 95g when it stopped working.
Doug

 

[television]

Hi Malcolm, good to have you back on the forum.
When my CLK was nearly out of gas, the A/C was working cool-ish but I got an occasional "hissing" from deep behind the dash. Since regassing (£45 from KwikFit) it's super-cold and hasn't hissed since. Correct level is (I think I remember) 780g of refrigerant and I was down to only 95g when it stopped working.
Doug

Hi Doug nice to hear from you , and thank you for your input.

I wish mine was that simple, it has stopped, its full of gas, so there goes another arm and leg when it goes onto STAR

 

[Veridian]

Hey Dirty Harry, I agree with the others, my E class started a rhythmic hissing a while back - and I was told by my local indy T&M Motors - Molesey(very good) that as you lose gas the hissing is the gas rapidly expanding in the evaporator - to be honest I guess its an enclosed version of somebody spraying an aerosol. But since the pressure is now low, the gas passes through the evaporator faster?.. Im at the limit of my GCE Chemistry/Physics here! However, got it regassed and the hissing stopped!

 

[Dirtyharry]

its a w203 cdi

i thought the gas must be low....thank you for all your replies.

much appreciated.