Heater fan non operational
 

Hello all,

I have a 2006 T&C, and neither the front or rear heater fan are operational. Fuse is good, I have switched the relays, and changed the resistor, but nothing has worked.

This van has driver, and passenger side controls, and there is no voltage at the controller, or at the resistor...I do not have a schematic for this of course, but being an electronic tech, I am very frustrated not having figured this out, any help would be appreciated.

The Front Control Module (FCM) sets the ground to both the front and the rear blower relay coils from a single output. May be a bad FCM or poor connection at the FCM/IPM interface - common.. You could try providing a new ground to each by slightly popping up each relay and grounding contact #85 to structure. If the fans spin you know you're missing that ground from the FCM.

Would you like the WD? Send me a PM with an email address included and I'll shoot it to you. How? Click User CP at upper left then Send New Message under Private Messages in left column

Thank you for your reply, I will try that right now. I would like to see what you want to email, I will send a pm with contact info in a bit.

You say the FCM, is that the controller on the dash board, or something else?

I supplied ground from pin 85 to negative on the battery, and the fans came on, now how can I isolate if it is a connection issue, or a faulty component?

AAAhhhhh,

I think the FCM is mounted on the fuse/relay block up next to the battery, is this correct?

You got it. Disconnect the negative battery cable before disconnecting the FCM.

Will the FCM need reprogrammed if replaced? I was thinking about installing a relay to supply ground when the ignition was on...

The connectors under the relay/fuse block have a little corrosion... I tried cleaning them the best I could, but still a no go.

The IPM is infamous for corrosion, either external on connections or internally, causing many electrical problems on the van. The fact you're seeing it externally may warrant taking it apart for a look inside.

You've confirmed you're missing the ground from the FCM. That points to the FCM being the culprit. Unfortunately, you have to ask the question what tells the FCM to set the ground. The wiring diagram sure doesn't make that clear so all I can assume is the FCM gets a command from the fan switch on the HVAC panel via the BCM and PCI data bus. You'll see that towards the bottom of the diagram. All you can really do is confirm the wiring and connections are good either visually or better yet proof the wiring with a multimeter. While in the IPM I would try to trace that whole circuit looking for anything amiss.

Use a relay to supply a ground? I'd be a little leary of messing with the data bus. It is a sensitive beast. It may work.

BTW- Sent the diagrams a bit ago.

LATE EDIT - The FCM is plug and play. No programing needed. Just make sure the part numbers match.

I can't access private messages, it brings me to a page that says:

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I will dig into more later in the week, I will be traveling for work, I thank you very much for the info you have provided, it has helped me a lot, this van has had electrical issues, and I would like to get things resolved. Again, I thank you for the help.