This 2002 Mercury Grand Marquis came in with a customer complaint of a blower motor that no longer worked. The customer also stated that up until this point it would work sometimes and sometimes not. This repair is also for Crown Victoria and Town Car applications. I guess I have gotten so used to this that I hardly ever test these systems anymore I just replace the blower speed controller. To test locate the blower motor at the passenger side firewall under the hood. It is just outside the left side of the picture below. Check for 12 volt power on the brown/orange wire (supplied through fuse 18, 30 amp in the interior fuse box) with the ignition on. Now check for ground on the orange/red wire. If both are present the blower motor is faulty. If no ground is present move on to the blower speed controller. It is located behind the rear of the passenger side cylinder head, under the heater hoses.
I would normally recommend doing more testing at this point but the harness is so ridiculously hard to get to, that I would rather buy a new $70.00 part and install it based on experience. If I still had a problem I would of course have to do more testing. Again based on experience, I have changed around a hundred of these things over the years to correct blower problems and have never had to go any further. With the exception that the blower motor also needs to be changed on older vehicles with a lot of miles. Of course you should have already checked that according to the above paragraph. I will sometimes do an amperage draw test on the motor if it is old or the mileage is high. A bad blower motor can damage a blower speed controller.
With the evap solenoid assembly out of the way you can kind of get to the connector and mounting bolts. The evap solenoid is easy to remove. Two hoses (fragile be careful), one vacuum hose, one harness connector and two mounting nuts. Removing the harness connector has always been a pain to me. The locking tab is located on the bottom side of the connector. By the time I have gotten my hand positioned just right to hear the latch click and release, I have no ability to actually pull the connector loose from the blower speed controller. The trick is to use a wide bladed, long screw driver between the edge of the connector and the blower speed controller. Line the blade up in the slot and twist to separate the connector once the locking tab is released. It sometimes takes several tries before God has mercy on you and allows it to come free.
Once you have unplugged the blower speed controller harness and removed the two 8 mm headed screws, you can sometimes wiggle the controller out of the car past the heater hoses. Putting it back in is a different story however. I do not know why I always feel compelled to try when most of the time I have to pull one heater hose loose. I guess because every now and then, it will come out and go back in with no problems.
The one heater hose as shown below needs to be removed from the pipe at the rear of the intake. The clamp is a little bit of a pain but not too bad.
Just a picture of the new controller be installed. I use a 8 mm swivel socket with an extension to make it much easier.
The controller is back in it’s place, the heater hose is back on the pipe and now it is time to put the clamp back in place. You can also get a clear picture of the harness connector.
It takes a little while to work the clamp back into place. Patience is indeed a virtue. After the clamp is back on it is just a matter of reconnecting the evap solenoid and topping off the coolant.
Just a picture of the new versus the old blower speed controller. This part is now available through The Electric Connection in the Motorcraft brand.