If it hisses in any position it is in need of at least lubrication. The rubber disk has tiny channels in it and the edges wear. The best thing to do is to just get a new one. It isn't that easy to get to the mode switch so when you take it out you might just as well replace the rubber part. The real problem here is when it is all dried up (after 20 years) and you turn it you run the risk of breaking the plastic parts because it is so hard to turn. When done right it should turn very smoothly and easily and not hiss in any position. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, Phil Priestley <phil@xxxx> wrote: > *This message was transferred with a trial version of CommuniGate(tm) Pro* > > I'm always hearing talk of mode switches hissing. Mine only hisses when > I trun the climate control to the off position. Other than than it > dosn't hiss. Is this the norm or is it leaking > > > > > > Phil Priestley > Alessandros 120 > (503)370-9951