Hi Guys I just picked up my first Benz (1989 300TE 280,000kms) and the first thing i have noticed when playing around with it is, man these things are well built. I have managed to fix a bunch of minor electrical gremlins and give it a good clean inside, what a mess. Anyway, I have now found a weird noise coming from right behind the AC button. It sounds like that brief hiss you sometimes get from AC when it is getting really cold but it stays on the whole time until i press the recirc button and then it goes away. Any ideas what this may be and pointers on how to rectify this?***UPDATE*** I just noticed that if i wiggle the fan switch in the off position the noise is intermittent. If I turn the fan speed switch onto the first indent (in between off and I) it goes away completely. I like the result but it would be good to know ther is nothing nasty going on.

The hiss could be a vacuum leak from a flap actuator pod or a vac line. One other momentary hiss I have is when the heating system kicks in during a cold start warmup or the compressor cycles on, I think it's the expansion valve hissing. Both of those hisses are momentary, not continuous however.

Rgds,
Chris W.
'88 300E