revdarkwing

All of a sudden, the climate control system in my '96 C220 stopped putting out hot air. It still blows air... and the LCD panel still allows controls.. but it simply doesn't put out any heat regardless of how high I turn it up.

perhaps connected are these two other new developments.
1. The outside temp display started showing temperatures that were much colder than actual temps and coincidentally, quit displaying entirely at around the same time the heat quit.
2. The cruise control now surges if activated before the car has had a chance to run for perhaps 5 minutes or so.
3. Also... if I put the climate control on "defrost" where the temperature goes to "HI", it then puts out heat.. but only on that setting. Auto... and directed flow both blow cold.
Any thoughts on where I should look first to locate the problem and fix it?

Thanks
Rev