2005 Grand Caravan- Front fans not working, rear fans fine

[shamilton777]

2005 Grand Caravan - All my front fans wont work at any speed (including the defroster which will be a problem soon!). The rear fans work just fine.

I'll be checking the fuses, anything else you can think of before taking it to the dealership?

Thanks in advance for any help you can offer.

[Airjer_]

There is a blower motor control module behind the glove box. It controls the blower motor speed based on the A/C voltage signal it receives from the switch. They are easy to check and condemn with a voltmeter.

[shamilton777]

Thanks for the Help. I'll check it and let you know!

[shamilton777]

Checked the Fuses and relays - all good there.

The module behind the glovebox seems to be the resistor(black, on the left, held in by two screws with a "5 wire plug" (all black and blue) on the left, and a "2 wire plug" (1 green, 1 black) on the right, and I'm told the telltale sign for that being the problem is that the fans will only run on high. This is not the problem I'm having - my front fans will not run at all.

Anything else you can think of?

Thanks again!

[Airjer_]

My bad you have a resistor. The automatic system has the module.
It is possible for the resistor to not allow the fan to work at any speed. It has a fuse built into it and its the first thing the ground side of the blower runs into.

The dark blue wire should have power to it all the time with the key in the run position. The black wire is the power going to the blower. The green wire is the ground side of the blower. You can check continuity between the pin on the resistor that the green wire goes to and the pin on the resistor that the blu w/gray tracer goes to. This would be the path that the high speed uses. If there is no continuity than that is a problem since the thermal fuse is in between these two pins.

[shamilton777]

Bought a Multimeter. The resistor unit checked out. It has a total of 8 pins, (diagram below)Numbers are the blue wires, letters are green(A) and black(B) wires. There is continuity between 3 and A, and 6 and B.

1 2 3 | A
4 5 6 | B

How do I use the multi meter to check if there is even power going into the unit to begin with?
There are only 5 blue wires going into the resistor - to pins 1 thru 5 - nothing goes to 6.

Sorry for the questions - I'm a bit of a newb to this... thanks again for all your help.

[Airjer_]

This is a ground side controlled sytem. Which means power is supplied to the blower all the time and the switch controls the path that ground takes. With everything unplugged you should have power (12v) at the blue wire all the time with the key on. (touch the black lead to ground and probe the blue wire with the red probe, make sure your meter is set to DC Volts)

There should be continuity between the black wire and green wire.

With everything plugged in there should be power on the black wire.

There should also be continuity between the two pins on the resistor that the blue wire and black wire go to.

There should be continuity between the green wire and the blue/grey wire.

[shamilton777]

Great - I will check all this tonight. Thank you, Airjer, for all your help! It is much appreciated!