elecrical problem or what?
 

In my '81 380sl, the heater nor the a/c blower motor will come on unless you jiggle the key in the ignition. After doing that, the a/c blows nice and cold, but the heat only blows cold? Thermostat was just replaced last week so that's not it. Where should I look next????

The obvious place to start is with the ignition switch. This is a problem that could potentially leave you stranded by the side of the road, so you should look into replacing your ignition switch soon.