A friend of my family has a 2000 lhs that has a couple issues, one is that the driver door doesn’t lock, leaks out of the radiator, doesn’t blow cold air at all even on low and the the transmission slips in first. What could be the problem other than the transmission issue? He got the car for $800 a few days ago.

 

Drivers door lock, usually solenoid assembly that is part of the door latch. Salvage yard part, interior door panel needs to be remover to replace.
Leaky radiator typically is split tank on passenger side.
A/C : These cars are known to have evaporators that leak, complete dash removal to replace if that is the case. Check all hoses and connections first but common issue.
Trans Slip (unusual) Stuck in limp mode more common with Speed sensors common starting point for 99-01 vehicles with solenoid pack for 02 and up.
This car could be big$$$ to save unles you and DIY. What engine?? 3.2 & 3.5 use a timing belt that must be serviced 7 yr/ 100k.so it should have been changed 2007,14 & 21. If not and it fails catastrophic engine damage will occur.
2.7 use a chain but the guides wear and water pump could leak internal to the engine oil.