Question about 2000 Mercury Grand Marquis
The fan stopped working regardless of the speed being set low or high, heat, A/C, vent, etc. I checked all the fuses, took the climate control unit from the dash, checked and cleaned all connections. disconnected the blower motor and measured the voltage. At low speed, I was receiving 2-3 volts and at high fan speed, 10-12 volts. I figured the motor was bad so I replaced it, but got the same problem. I took both the new and old blower motors and applied external battery and both motors worked. I figured maybe the connector itself was bad so I cut the wires and connected directly to the motor and it still did not work. When I checked the voltage with the motor attached, I was not getting any reading. Something is causing a voltage drop when the motor is connected, but I don't know how to proceed?
It's even odd that you were getting a step-type voltage when you first checked.
Many speed regulators are simple tapped resistors with the switch selecting which tap is connected to the motor.
More elegant controls would use a semiconductor (transistor) and a few other components to supply step-variable voltage to the motor.
To determine which is used on your car, you will at least need the electrical diagram for it, preferably an aftermarket service manual - Haynes or Chilton should be available at least in the US and Canada.
Those will contain not only the electrical info you now lack but possibly instructions that will aid in locating the controlling circuit.
I suspect that circuit is faulty; if the resistor type, it will be a device with mulitple taps, if solid state, a few parts on a small board.
Posted on Jun 18, 2008
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Posted on Jan 02, 2017
SOURCE: heat-a/c blower motor stopped
check for ground going to fan. If there is no ground replace a/c control panel located under radio it what you use to turn on the heater/ a/c
Posted on Aug 27, 2008
I had the same problem with my 2000 Mercury Grand Marquis. I ended up replacing the blower and the resistor which is on the passenger center side of the firewall tucked in where it is hard to get to. Everything worked fine for about two years. It just went out again here about a month ago. I am going to try to replace the resistor again, but I am wondering if it doesnt have something to do with the climate control switch. I do not want to replace the same part every year or two, so if anyone has a idea of what could possibaly be the bigger problem, please let me know.
Posted on Nov 22, 2008
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