The light that won't go out

I have a '94 Mercedes S with 181,000 miles on it. The engine light has been on for two years. The car has been to a dealer nearby many times and at one point, they tried putting in a part that they ordered from Germany but it did nothing. So for two years, I continue to ride with this light on with no apparent harm. Recently, the fan for the heater stopped going on. It happened suddenly. It takes forever for the heat to come in but you can kind of feel it. We left the car for a weekend while we were away and when we got back, the battery was dead. After having it jump started, the blower for the heater came on! The battery was checked and it is fine as were the fuses. The fan/blower worked for the rest of the day. The next day we were back to square one - no blower. I am wondering if the engine light and the fan/blower for the heater issues are somehow related? BTW I love this car - annoying as it has been and as expensive as it has been for me to have it repaired - and would like to NOT have to spend a fortune on this. Is this an electrical issue or? Any advice would be appreciated! Thanks so much!

The dealer has left you with an illuminated CEL for two years?! That is very strange and unacceptable. No, the problems are probably not related and you should take both of them to another shop.

Did the dealer pull any OBD-I codes off the computer? If so, what were they? If you go to another shop, get them to pull the trouble codes and let us know what they are. OBD-I codes aren’t as available as OBD-II codes, which are standardized. But there ae some Benz people around here who may be helpful.