1988 Mercury Grand Marquis blows hot air when accelerating uphill and downshifting. Does this with or w/o a/c running. What is causing this?


Asked by Apr 03, 2012 at 01:52 PM about the 1988 Mercury Grand Marquis

Question type: Maintenance & Repair

The a/c will temorarily blow hot while downshifting during acceleration. Also, warm air comes out of vents w/o the a/c or ran running during acceleration and downshift. Vacuum issue? Otherwise, the a/c and compressor work normally and blows cold.

1 Answer


Very possibly vacuum issue. Hook up a vacuum gauge to manifold vacuum. If you can run gauge inside car while driving and reproduce symptoms and watch gauge you should be able to confirm or eliminate vacuum issues. You should have 17-21 at idle. Look for steady and proper vacuum while driving. No load high vacuum loaded lower vacuum, but steady.

2 of 2 people found this helpful.

Your Answer

Mercury Grand Marquis Experts

  • #1
    Tracy Hooks
  • #2
  • #3
View All

Related Models For Sale

Used Lincoln Town Car
21 Great Deals out of 1,447 listings starting at $1,850
Used Ford Crown Victoria
3 Great Deals out of 922 listings starting at $1,999
Used Ford F-150
2,535 Great Deals out of 221,934 listings starting at $1,222
Used Dodge Charger
256 Great Deals out of 33,484 listings starting at $495
Used Ford Mustang
294 Great Deals out of 38,678 listings starting at $1,995
Used Honda Accord
565 Great Deals out of 92,859 listings starting at $1,495
Used Cadillac DeVille
1,249 listings starting at $2,499
Used Chevrolet Caprice
134 listings starting at $1,350

Used Cars For Sale

2011 Mercury Grand Marquis For Sale
15 listings starting at $6,934
2010 Mercury Grand Marquis For Sale
66 listings starting at $2,900
2009 Mercury Grand Marquis For Sale
5 Great Deals out of 81 listings starting at $3,400
2008 Mercury Grand Marquis For Sale
101 listings starting at $2,999
2007 Mercury Grand Marquis For Sale
7 Great Deals out of 98 listings starting at $1,900

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.