2003 Chrysler Town and Country Van came in with the complaint of the blower operates on high speed with key on and cannot be adjusted down. This procedure will also apply to Dodge Caravans with auto a/c. The controls and indicators seemed to work normally. I checked the wiring diagram and component locator and found that the blower power module is located behind the glove box. Good place to start.
After opening the glove box there are two stops the have to be depressed inward in order to drop the box down.
The blower power module is directly behind the lowered glove box. It is held in place by two 8mm hex head screws.
After removing the two attaching screws, the blower power module can be positioned for testing.
Turn the key on and while manually rotating the blower switch from low to high you should see a voltage change between about 2 volts (high)up to about 10 volts (low) on the blue/light blue wire. It is the middle wire in the left connector pictured below. Because the blower was working on high speed there was no need to do any other testing, however if you were to have low blower or no blower you would need to test further. Check for 12 volts – on the black/orange wire and 12 volts+ on the dark blue wire in the three wire connector. If either is missing check respective fuse and ground connections. Next check for 12 volts between the blue wire and the dark blue /yellow (sometimes black as pictured below) wire in the two wire connector to the right of the pictures. If either signal is missing in the two wire connector and the three wire connector tested good then the power module is faulty. If 12 volts power and ground are present then the blower motor is faulty. Usually bumping the motor with the key on and the blower switch on high will make the motor work for a little while because it will reset the worn brushes.
Three wire connector:
Black/Orange wire should have a constant ground.
Dark Blue wire should have 12 volt switched power from the front blower relay. The front blower relay is located in the Integrated Power Module (underhood fuse box).
Blue/Light Blue wire should have a varying voltage from about 2 volts(high blower command) and a nominal 10 volts(low blower command).
Two wire connector:
Check for a nominal battery voltage reading across the two wires. Key on and blower set to high.
I removed the mounting screws to gain better access to the wiring for testing.
Be careful to keep the aluminum cooling fins away from the metal brace for the glove box. It will complete the ground circuit for the blower motor and will scare you when it sparks.
Place an insulating cloth between the aluminum fins and the brace if you want.
A good look at the blower power module.
Installed the new blower power module and all is well.
I would disconnect the module completely and then check to see if the fuse blows to confirm that there is no problem in the wiring or switch. The module will get very hot as there is no air flow across it with the blower disconnected. DO NOT try that test with a new module as it will be damaged. The rear module will be typically be within 12″ of the rear blower motor. The rear blower is in the passenger rear of the vehicle behind the trim panels.
Great information, thank you. So my situation is that my fuse keeps blowing. I took the blower module out and the wires and wiring harness is melted. I ran the first test with a new fuse and found that I was getting the correct voltage until I hit high and then the fuse blew again. I had the second wiring harness disconnected just to make sure it wasn’t a seized blower motor cause it to over heat and blow. I touched the module and it was extremely hot. I am trying to figure out if it is a blower module or a short in the wiring harness. Any thoughts? Also, where is the rear blower module located?
Thank you.
Are you sure it is the module and not the blower motor that is being affected by banging on the unit?
Sparky, if my a/c fan fails to come on (and that is often), I can get it to start up every time by banging on the power unit behind the glove. Is there no way to clean one of these babies?
This is the second one of these that has gone bad on me.
I have never dealt with this issue before with this system but let’s try a few things. First of all, check the voltage at the battery, engine off and engine on. If the battery voltage goes over about 14.5 volts (depending on outside temperature) there is a charging system problem. The blower would simply be a symptom. If the charging rate is okay, then you will need to determine if it is a feedback issue or voltage issue. My preference would be to install a battery charger on the battery and set it bring the battery voltage up to 14-15 volts and then see if the blower does the same thing. Key on but engine off. If it does then something in the system does not like the slightly higher voltage. If it works normally then there is a feedback issue (could be as simple as dirty battery terminals). f you need further assistance please email me. My email address is located on the “Contact Sparky” page.