Greetings Everyone.

'06 LR3: Heater/AC blower motor suddenly quit. Replaced fuse, relay, control module, and motor. Still does not work.
I jumped the ground from the motor to an earth post in the foot well, and now the motor works but it’s on high no matter what the dash switch position. The motor is either off or on high.

I was hoping someone had a work-around that didn’t involve tearing into the wiring harness.

If the control module is grounded, maybe it’s a bad ground at the module?

Thanks in advance for any help, and Happy New year.

 

I'll take a stab at this one...

By jumping the blower motor to ground, you are bypassing all speed control. When the relay trips on, you have full battery power to the blower. Fully expected behavior by the wiring diagram below.

You replaced the "fuse, relay, control module, and motor." By "control module" I'm assuming you mean the blower motor control module near the blower motor, and not the ATC Automatic Temperature Control module mounted in the center dash.


It looks to me that your ATC module in the center dash could be the culprit. There's a document (attached) that shows what each pin on the ATC module should be doing. The pins don't exactly correspond with the wiring diagram, not sure why, but you should be able to narrow it down to test.



I spent hours troubleshooting my "low-to-no power to the A/C compressor's refrigerant solenoid valve. These documents lead me to a pretty firm diagnosis of a failed circuit within the ATC module. I ordered a used one from Ebay which solved my problem.

Good luck!

 

Thanks a ton, P-Bod,
I appreciate the diagrams. By Control Module, I'm speaking of the one located by the blower. My dash switch is functioning like it should because it controls the rear blower motor speed just fine.
I'll check the diagrams and see if I can chase this one down.
Thanks again!
Scott

 

It looks like the rear fan speed control comes from a completely separate output circuit from the main ATC module. I may not be reading this correctly, hopefully someone will correct me if wrong.

 

Good to know, thanks. I haven't had a chance to really take a good hard look at the diagram. My eyes tend to glaze over when it comes to wiring diagrams!
I found a complete climate control module for $54 and a 90 day return policy. Tested and works they said. I'm going to try to chase down a ground and if everything looks good in the wiring harness, will pick up the climate control module. I'll let you know how it goes. Thanks again.

 

P-Bod,
According to the diagram, the front blower motor control unit is grounded at C2606 and the motor itself is grounded at the module at 4/5. I'm thinking that there might be a bad ground at one of those points. Am I reading the diagram correctly? Thanks :-)

 

I think the blower control module terminals #1&3 gets a signal (variable voltage per diagnostic doc) from the LT GRN/Black and GRN wires coming from the ATC then allows switching to ground accordingly. This is only a semi-educated guess on my part. At the blower control, it looks like you should have 1.5 to 2.8v on the GRN wire at terminal 3 and the LT GRN/BLK wire at terminal #1 should read 6.3 or 3.3v per the diagnostic doc.

 

I think you are right. I'll put my meter on it. There might be a break @ 1&3 from module to ATC @19&20. I'm still thinking a bad ground somewhere.
The diagram is super useful. Thanks again

 

I think that wiring diagram is wrong for #19 and 20 at the ATC. This one attached says #17 and 18 which corresponds to the diagnostics doc. which makes more sense.

 

P-Bod,
I meant 17 and 18 like your new attachment. Thanks for this new diagram set - it's super helpful and it does make more sense with the steps in the diagnostic document.
I'm stoked to chase this down Saturday morning. I'll let you know what I find.