2005 Merc Grand Marquis w no a/c air flow from vents on front of dash

10

Asked by Jun 08, 2013 at 12:39 PM about the 2005 Mercury Grand Marquis GS

Question type: Maintenance & Repair

My '05 Grand Marquis has 140K miles. Recently the front a/c vents quit blowing cold
air.  For the next 2 weeks we drove it with cold air coming out of the vents on top of
the dash only. After 2 weeks, a/c air flow on the top of the dash also quit.  Yesterday I
R&R'd the blower motor.  Now it's back to blowing cold air out of only the vents on top
of the dash again. I then checked the a/c system switch; which stays in the same
mode (normal a/c I think) in all positions except vent, and off. So "mix", normal a/c,
high a/c, "floor" etc positions all blow cold air out the top of the dash. Off is still off,
and vent is still vent.  If anyone can suggest what part I should now replace or what
action I should take now, I'd appreciate it very much.  Thanks.   Les   Tucson

5 Answers

28,175

you either have a vacuum leak in one of the lines under the dash or a bad actuator. take the control head out and see if you have vacuum to it. the black line is the feed line I believe.

10 of 10 people found this helpful.
25,315

Be sure to check the vacuum check valve and reservoir under the hood. They supply vacuum to the system under a heavy load (like climbing a hill). Usually, when these start to fail, you'll experience the AC switching to the Defroster vents when you pass someone.

9 of 9 people found this helpful.
69,475

Check for a broken/ disconnected vacuum hose in the engine compartment. It should connect to the intake manifold. When the climate control system loses vacuum it automatically defaults to defrost. HTH. -Jim

5 of 5 people found this helpful.

Have the same problem...actuator motor...didn't have money to spend $600+ so investigated and found if I take the battery cable off it would retest everything???you can then fiddle with the a/c and get it on cold again...been doing this for 5 years and it works!

3 of 3 people found this helpful.
20

I had the same problem and had to replace the tiny O rings that connect the vacuum hoses to the actuator. It's a job, but the O rings only cost me $1. If you replace the module, it's $700? Have you gotten it fixed yet?

2 of 2 people found this helpful.

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