2003 Mercury Marquis Climate Control Fan Stays on High at a

2003 MERCURY MARQUIS
76,000 MILES • V8 • 2WD • AUTOMATIC
Avatar
TOMLAQ
  • MEMBER
  • 3 POSTS
Had my car go through its annual safety inspection and when it came out of the garage bay the heater/AC fan stayed on high speed at ALL times. Even when I hit the OFF button on the climate controls. In fact even when I turn my ignition key to the auxiliary position the fan comes on high without the climate control on at all.

Seems like too much of a coincident that it started right after having the safety inspection, which of course plugs into my cars computer.

I had the dealer replace the control module about two years ago when the blower stopped working. I can only assume the module is the problem again.

I�m guessing the �Blower Motor Speed Controller� wouldn�t cause my problem.

Do you think it�s possible that the garage computer connection to my car created the problem or just a big coincidence?
Nov 8, 2009 at 8:38 AM
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.
Advertisement
Avatar
TOMLAQ
  • MEMBER
  • 3 POSTS
A faulty blower motor speed control resister causes the fan to stay on high even when the climate control system is turned OFF. In the OFF position the fan apparently runs on very low speed.
Nov 14, 2009 at 8:31 AM