"THANK JOEY"HI GUYS GREAT WEBSITE Ihave a problem with the heat in my 96 markviii,after warming up or driving for 30 minutes set at90 it still blows cool air.I took to a mechanic he flushed it,changedTstat,check vacume lines and ranthe computer on the blend door actuator it states is working just fine OH I almost forgot to mention the car ran idle for an hour in the shop and sure enough there was HEAT.while driving 15 min no heat & set at 90

Hi JRMARK,
Were you able to find out anything about your lack of heat situation? I have the same problem in my 97 Mark 8 LSC. There wasn't much in the threads posted on the subject and the links that were put up about fixes are now broken.
Spanky

Off the cuff, does the Mark 8 have a controlled valve (electric or vacuum) that blocks off engine coolant from the cabin area to keep heat out when using the A/C? I would think so, but I am not very knowledgeable about FN-10's enough to say w/ certainy. Should this valve be weak, it could be an intermittent problem not seen by the EATC or MIL.

Could be the HVAC head unit.

Scroll down to the middle and look for Jibit's post to run a diagnostic.

http://www.lincolnvscadillac.com/showthread.php?t=9671&highlight=EATC+test

Hi JRMARK,
Were you able to find out anything about your lack of heat situation? I have the same problem in my 97 Mark 8 LSC. There wasn't much in the threads posted on the subject and the links that were put up about fixes are now broken.
Spanky
SPANKY ckeck out the other thread on GOT HEAT