This applies to an '88 760 turbo with electronic climate control. A few days ago I uncharacteristically mashed the gas pedal and as the car rocketed out from under me I heard a distinct pop and then a slight hissing from behind the dashboard. The line that attaches to the speedo cluster turbo gauge was suspected but the turbo gauge continues to work normally. And when I first start the car and until the engine produces enough heat to activate the climate control system (I live in the northeastern US where the temp. is near 0 F each morning), there is no noise. Then when the system clicks on, the hiss begins. What lives way over on the left side of the dash that is related to this noise? The climate control system is behaving about as it always has, the knob has to be set to 80 for the car interior to be tolerably warm, and I generally like a cool car. Any guesses?