View Full Version : 1988 Grand Marquis

09-11-2008, 01:52 AM
either on the vent or air conditioning settings when I excellerate the air turns to heat and then when I let off the gas it returns to outside air or AC.

09-11-2008, 04:03 PM
rogerd52 - You have a vacuum leak in the system.

09-12-2008, 03:00 AM
Where would be the best place to check for the vacuum leak? How do I check for the vacuum leak?

09-24-2008, 04:28 PM
Rogerd52 - Check around the firewall near the windshield wiper motor. It's a little black vacuum box which you should see a vacuum line connected to it. If not replace or re trace were its running from and replace it with a new one or hook it back up