1989 230E W124, recently bought, have some questions
 

Greetings everyone! Last week I became an owner of the gray(metallic) 1989 230E, wonderfull 2.3L engine, nice exterior and clean interior.
The car handles great. Just feel like I am a king of the city roads. However, the car has some problems and question only the forum members can answer. Sorry for asking you so many questions. Please help if you can. My questions are:
1. Yesterday when I started the engine and was admiring at the oil pressure gauge staying at max., suddenly the instrument panel electronics stopped working including oil pressure, fuel level meter, water temp and tachometer. After that I can hear whining sound from the front left speaker. The sound appears when ignition is on and also with engine working and disappears when the turning lights are turned on. What can this be? Thinking it is a shortage I removed the stereo, unhooked the front speakers but that did not help.
2. There is always hot air coming from the wents when the vent is on regardless of the position of the 2 wheel controls. The instrument panel LCD is showing -38 degrees C. Does this affect heater. How do I turn off the heat? Why there are 2 wheel controls for the heater, isn't 1 enough?
3. At speeds above 100 km/h (60 mph) I can hear wowing sound coming from the back. I also hear a nock from the back when I push the gas pedal or when shifting. Seems like it is back parts of the rear wheel drive. Is this thing expensive to fix?
Thanks for reading.

Welcome to the forum Hurshi.

My guess is the howling sound is your tires, OR seeing as you just got this car I would drain and replace the diff fluid just in case. The knock when you change gears is probably a worn out rear shaft coupling, OR it could be any of the number of bushings in the rear so get the car up on a machine and have a good look at all the links and subframe mounts. If your heat is not turning of you may have a vacuum leak, OR check this thread out..http://www.peachparts.com/shopforum/tech-help/36232-only-heat-coming-out-vents-190e-2-3-a.html?highlight=hot+air. The LCD display does not control the inside temperature of the car.
Check your fuses for the short and see if any of them blew. Also check the fuse(s) on your OVP relay, red relay located behind the plastic behind the battery.

In regards to #1, check the ground cable coming off the negative battery terminal. Could be loose or dirty. Also check the end of the ground cable where it attaches to the body.
Whining speakers often indicate a bad ground.
This can be intermittent.

As for #3, noise from rear at speed could be the driveshaft support bearing, rear bearings, or several other things. Tough to isolate from description.

Knocking while accelerating or shifting is usually the driveshaft flex joints or the transmission mounts.
These last 2 are not particularly expensive to address.

Welcome to the neighborhood, and best of luck.