2003 Grand Marquis replaced heater core, now air only blows out floor vents why?


Asked by Oct 08, 2015 at 03:09 PM about the 2003 Mercury Grand Marquis

Question type: Maintenance & Repair

our a/c stopped working, we were advised it was the heater core. The air was blowing fine out of all the vents. After replacing the core, we get the car back, the begins only flowing out the floor vents. Is this just a coincidence? They are now telling us they need to replace the control valve.

4 Answers


vacuum leak...whomever fixed it needs to do it again ..not the heater control vavle...

1 of 1 people found this helpful.
Best Answer Mark helpful

he told my husband the control valve box was bad....is that possible

1 of 1 people found this helpful.

Kelly is right!. Vacuum leak for sure, the HVAC doors are controlled by it. I suspect they forgot a connection when they put the dash back together. DO you hear any hissing? Maybe it is the control door, but they broke it when they took the dash out, so let them fix it on their dime, not yours since you already paid.


It's the the A/C door blend actuator, set incorrectly.Dismantle everything again and manually close the flap door(facing the dashboard;move to the front-right. Then place the slot on top.Just thight the 2 front bolts and rotate the selector to verify that the air comes out, in Defrost,down on Heat and thru the vents in A/C mode.Don't use the rear 2 bolts they are a pain in butt to reach.Hope this works. Peace. Love , Luis.

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