The speedomoter on my 1993 corvette has been working off and on. Finally stopped working . How do I fix this?

check your fuel pressure should be 35 to 42 with key on engine off,and about 5 to 7 more with engine running and vacuum line off the regulator,also check your fuel regulator with vacuum off it should be dry if it is wet with gas it is bad

Does the ac unit fans come on? Also if it does come on is it only on bottom floor vents, or defroster only.

you need new headlight

It is likely you have a defective speedometer cable, pull the end out of the ****** and turn it with your fingers and have someone watch the needle, it should jitter a bit, turn it clockwise and counter clockwise while you do this test, replace as needed, the cable is cheap and is available here. ATP Part # Y805 Price $11.71 (USD) Source www.rockauto.com

Are you fully charged though? If you don't have a full charge the clutch will not kick in.

The cooling fan relays are located on the upper radiator support in front of the left front wheelhouse.

you have 2 relays for your fan, primary and secondary
their controled by the PCM according to the temperature

Replace the seat motors. that's what you get for buying a Corvette!

Replace your knock sensor.

There is a way to retrive the diagnostic codes in the A/C system by holding 2 buttons at the same time on the panel. I did this many years ago to solve a problem on my '92 Roadster. I got the info from corvetteforum.com Post your problem at corvetteforum.com. There are many experts there that will help.

MY POWER SEATS WILL GO UP & DOWN AND WILL TILT FORWARD & BACKWARDS BUT WILL NOT GO FORWARD OR BACKWARDS. IT JUST MAKES A HUMMING SOUND WHEN TRYING TO GO FORWARD OR BACKWARD. IS THE POWER SEAT SYSTEM A GEAR SYSTEM, OR HYDRAULIC SYSTEM?