I wouldn't expect A/C to work on any car this old. It's simply a tough system to keep working. Requires patience and money, and sometimes quite a bit of troubleshooting. Could be a $1 o-ring, could be a $300 compressor. Either way requires $100 or so of vacuum purge and recharge, per attempt to fix. It could have multiple problems and may require 2 or 3 attempts in order to get all the problems resolved.
The heat ought to work well on any 240. They do have problems with the heater fan. I never heard of a relay needing replacement, though there is a resistor that controls the fan speed. It's buried in the dashboard along with the fan. Replacement IS possible with normal hand tools. However it's NOT a small job and requires either some contortions under the dash or complete removal of the upper dash.... one way is harder, but you leave everything together, the other way is easier for access, but you remove (and have to reinstall) more stuff.

If the crash damage was fixed right, there's nothing to be afraid of. Professional body shops can do a fine job. The OD issue could simply be the relay, or the wiring under the shifter. I've fixed both in my cars. The solenoid too is something that can be replaced by a home mechanic, if in fact that is what's wrong. Only has two socket-head bolts on it. Just a filthy area to work in.

I would spend the money to have it looked over by a professional mechanic, and have a list made up of needs. Then evaluate what you can afford, what you can do yourself. A lot of maintenance is simply time consuming more than anything. The only other issue with an '89 is that it's the first year for the "new" LH 2.4 fuel injection- if it's never been changed out, the car has a weak (and expensive) engine computer. (Check ebay for prices on a 561 or the upgraded 951 unit). They are subject to failure which will leave you dead in the water. I can't believe it would make it to 200K without being replaced once... so maybe someone's already spent the money for it.

Have it checked out and make your decision based on it's needs.
--
Rob Bareiss, New London CT ::: '86 244DL- 215K, 87 244DL- 230K, 88 744GLE- 198K, 91 244 180K