tecumseh_bill

I have a 2003 Grand Marquis LS Ultimate Edition. When I have the air conditioner on, the cold air comes up through the defrost vents at the windshield. After a minute or so the air conditioning finally comes through the dash vents as it is supposed to. This happens when I have Max A/C, Normal A/C or Automatic Climate Control on. I took it to a reputable shop and they diagnosed it as the vacuum door in the heater box. Supposedly it was not operating properly. I had it replaced and I still have the same problem. Does anyone have any suggestions? Any help would be appreciated.

Johnny Mullet

I would check the vacuum line that runs through the firewall first.

tecumseh_bill

Thanks for the response, Johnny. This has all been checked. All hoses, connections, etc. have been checked and double checked. All is good there.

tecumseh_bill

Turns out that it was the "Head Control" this is the unit that controls the climate in the car and is visible on the dash. when it messes up the air blows out the defrost. New ones in Canada are $1000.00. I had a used on installed. There is a waiting list for these things. The only way to get them is to wait until someone totals a Grand Marquis or Crown Vic. This sounds like a design flaw.

Hope this helps somebody.