2006 Mercury Marquis venting

Need to know what Marquis you have GS, or LS. IS the climate control automatic or manual? The MPH may be a selection on the dash info center, otherwise if the trans shifts properly you may have a bad dash cluster. Turn signals, turn on left signal and compare the rear lights with right turn to see if there is supposed to be 2 bulbs flashing, if one of them is out it will cause a fast flash, same goes for front, see if maybe the side marker light is out causing the fast flash

Sorry for the delay in getting back to you. You will need toput theautomatic a/c system in self-diagnostic mode.
Turn key on, engine off
Press Floor and off at the same time, within 2 seconds press the automatic button.
It will show a tracer going around the display window, it may take up to 30 seconds for it to do thetest, but it should spit out nay codes it has stored, they should tell us what is wrong

How long did it take for that to come up? That is the system exiting self test, according to Mitchell it shouldnt go to that screen unless you push the defrost button, which will clear any codes that may have been in there. This may be an issue with the module, does it only act up when the a/c is on and not the heat?

Also check under the hood for any broken vacuum lines that go to the firewall, sometimes these systems will mix vacuum and electric for the controls