Dead blower motor on Caravan
Most problems with blower motors are related to a bad resistor block. But if you're unlucky enough to have a different problem, here's how to troubleshoot.
Here are the system basics. Chrysler has power flowing to the blower motor at all times when the key is on. The ground is provided through the fan switch and resistor block.
There are two fuses for the blower motor. Fuse #12 (10A) sends power into the Power Distribution Center (PDC) on a white wire. Inside the PDC, that power goes into the coil side of the front blower motor relay. When the key is turned to on, the relay coil grounds and closes the contacts that provide power to the blower motor.
The second Fuse #21 (40A) sits in the PDC. It sends power into and out of the switched portion of the relay. From the relay, power flows directly to the blower motor on a Dark Blue wire. If the blower does not work, check the Dark Blue wire at the motor for 12 volts with the key turned on. If you're not getting power there, remove the relay and jumper between the relay terminals #30 and #87. If you get power on the Dark Green wire, you've got a bad relay. For a relay diagram, click here.
If you have power on the Dark Green wire at the blower, check the Black/Tan wire coming out of the motor. You should have 12 volts there too. If you have power on that wire, move on to resistor block. The blower motor is looking for ground in order to run and the Tan/Black wire is the ground feed into the resistor block. Test for 12 volts on that wire with the key on. Then with your voltmeter hooked to a good ground, check each of the other wires for reduced voltages. If you get voltage at each terminal, the resistor block is good.
Now, before you condemn the switch, check the black ground wire at the switch to make sure the switch has good ground--everything flows through that ground wire.
There you have it, the complete diagnostic procedure for a blower motor on Chrysler minivans (without automatic temperature control--that's a whole 'nother animal).
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© 2007 Rick Muscoplat
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