83 300SD heater won't shut off & Cruise doesn't work

[JBC]

I just purchased an 83 300SD and I am trying to fix all of the things that don't work. The first is the heater won't shut off. The fan will change speeds and the vent selector switches all seem to work fine. The rotary rheostat seems to work, because when I turn it all the way to cold and click it to min, the fan blows on high. As I was driving it in this morning with it on the coldest setting, not clicked into min, it gradually started blowing cold air.

Next is the cruise control doesn't work, and I'm not sure where to start looking for that problem.

Any suggestions would be greatly appreciated.

[JBC]

Also, the speedometer is about 4.5 mph slow. Is there anyway to fix this. I need an antenna too, and I see two diferent types; toothed and smooth. Do i just take the side of the antenna motor off to see what kind and is that how you replace it?

[talonlover]

The climate control seems to be working fine to me, it does take a while for the automatic climate control to make adjustments, so you may try it some more and be patient with how long the temp takes to change. As far as the cruise is concerned, 90% chance it's the cruise amplifier. A simple and fairly easy change if your a acrobat! It can be hard to get to for some cars, Look for it in the driver side footwell area, probably close to the firewall and dash.
Most likely your antenna mast is toothed, but the only way to tell is to remove the old mast and check it. takes about 5 minutes to replace. replacement masts are around 30.00 form MB.