Grand Marquis 2002 A/C
Asked by Mario Jul 20, 2022 at 12:11 PM about the 2002 Mercury Grand Marquis
Question type: Maintenance & Repair
My AC does not turn on in a regular basis, but if the knob is on high it will randomly turn on and off. If i try to regulate the speed it will turn off again. When it turns on the air comes from the defrost.
Any idea what the problem could be?
Thanks
2 Answers
Sounds like more than just one problem. Servo motors control blend doors, they can be either vacuum or electronic, if you have a digital readout on the control panel for the heater then they are electronically controlled, if not then vacuum controlled, the on and off could be blower motor on its way out, bad blower motor switch, wiring issues. If you are wanting to tackle this yourself then you need a complete heater control system diagram for your vehicle.
Trippmeister answered about a year ago
You've got so many problems, I wonder if it could be the electronics controlling everything. Especially if it's the system with electronic temperature control. My car had the manual control, so I never had to dive into this, with the blend doors, etc. It could be as GA said, bad blower motor and stuck blend doors.