I have had both problems in my 1986 420SEL. Sometimes I can get nothing from the vents but blasting hot air. Usually if I stop and shut the car off and then restart it works like it is supposed to. I understand quite often the culprti is the control push buttons. Also, for two years my cruise never worked really well, but lately it has been working fine - most of the time. I think the problem here is usually either the amplifier or some problem with the sensor up behind the speedometer, and occassionally using the wrong type of bulbs in your brake lights cause a surge or something to shut it off. (It is designed to disemgage when you put your brakes on, and it tells you are putting your brakes on by the brake lights going on). Have it checked out, I find these are minor inconviences, but I'm sure you'll enjoy your car alot more if you get them fixed.