1999 Mercury Marquis Rev's up

1999 MERCURY MARQUIS
173,700 MILES • V8 • AWD • AUTOMATIC
Avatar
LUCKIE9
  • MEMBER
  • 1 POST
In the fall I had a heater core replaced and since then when the heater is on, the car revs up. Recently when it snowed, I let off the accelerator and the car went by itself. The only time it does it is when the heater is on.
Feb 12, 2010 at 2:03 AM
Advertisement
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,240 POSTS
It is normal for it to rev when the defroster or AC is on. Is that what it does, or is it when the heater itself is on?
Mar 24, 2010 at 4:24 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.