What makes the 1994 eldorado overheat?

Sounds like the front of the radiator or A/C condenser is clogged up...take a water hose and try to clean any debre from the front, so air can pass freely...

are your cooling fans working, do you smell exhaust if you let it rin with the rad cap off if you do its head gaskets if not do you have agood waterpump impellers sometimes go bad

The mechanic is probably right. You can see for yourself by looking inside the radiator. Make sure everything is cold, remove the radiator cap and look at the ends of the tubes. If you see lots of lime buildup or other foreign material, it may be time for a "rodding out" or re-coring job. Sometimes you can improve the situation with a cooling system flush and fill, but if the mechanic isn't trying to sell you that, it's too far gone.

There is a possibility that the engine temperature sensor is reading high. Is that what was already changed?

check coolant levels. Does the car overheat? check fans.

Is the fan now working? Your engine will continue to overheat if you have not fixed the fan. Check the fuse for the fan, connectors, and replace the fan if necessary.

check engine temp sensor if ok check fan relay

one test to do, on the spot rev the car at 3000rpm, if it overheats you have a radiator probem, blocked etc, if it still wont overheat and will only overheat while driving then water pump the problem, its not pushing enough water under load, i would advise check radiator first.

check to see if the catalytic convertor is red hot after driving it,it could be plugged,it may also be a sticky thermostat,

FANS DO NOT COME ON UNTIL AROUND 235 DEGREE'S F, DID U KNOW THAT? WHAT U HAVE IS A NORMAL CONDITION, I AM A GM TECH I KNOW THIS FOR SURE.

take a look at the hoses on the radiator sometimes they will collapse and stop the flow of water under high rpms