Blower is always on when the key is on. - Diesel Forum

TDIDog · 01-16-2013, 03:50 PM

I guess I could let you read the title and guess, but since I need help, I'll provide more information.

2006 F350 Electronic Automatic temperature control. 142.000 miles.

FICM was bad. Low voltage and all of that. While testing, I noticed that the heater blower was on full speed and I couldn't shut it off even with the main EATC controller switch turned off and the display blank. hmmm That's odd.

New case half and it starts and runs fine, but the blower is still on full speed. I checked codes in the EATC controller and nothing is there. It passes KOEO tests.

I can watch the switches with my scanner and everything works... Well, not quite. I can press the fan speed on the dash and the scanner shows the button pressed up or down, but if I push the button on the steering wheel, the lines go up and down on the display, but the scanner doesn't show the switch pressed. To me, these two things contradict each other.

When doing tests with the scanner, the blower motor will shut off until I do the test. When testing fan speed with the scanner, the speed stays the same: full speed ahead, regardless of what % it should be at.

I can pull the heater motor relay and the motor shuts off. There is always battery voltage at the signal wire on the relay. The relay puts power to the motor, then the speed controller controls the ground for the motor. If there is a short to ground between the motor and the speed controller, that would give us full motor speed all the time, but, A: how likely is that, and 2: where is the speed controller located in this truck, and 3: why is there power to the relay all the time the key is on?

Hopefully someone has run into this and I just didn't find anything while searching.

Thanks.

TDIDog · 01-16-2013, 04:21 PM

So where is the blower control module? We found on another forum that this solved the same issue for another guy, but i don't know where the blower control module is located.

Thanks.

rodboro · 02-02-2013, 04:24 PM

Did you get the answer to this? It is on the passenger side firewall.

rodboro · 02-02-2013, 04:25 PM

I had the same problem and it was the module.

TDIDog · 02-02-2013, 04:47 PM

The module that I found is integral to the heater control buttons/switches. I don't know where things are with this right now.

rodboro · 02-03-2013, 06:39 AM

try this link, it has a diagram of where it is located.
http://www.justanswer.com/uploads/fo...r_risistor.jpg

It is called a blower resistor. I had the same problem last year and this fixed it.

runs about $20 at Discount Auto Parts and Accessories - PartsGeek

much more at the dealer!

TDIDog · 02-03-2013, 10:40 AM

Quote:

Originally Posted by rodboro

try this link, it has a diagram of where it is located.
http://www.justanswer.com/uploads/fo...r_risistor.jpg

It is called a blower resistor. I had the same problem last year and this fixed it.

runs about $20 at Discount Auto Parts and Accessories - PartsGeek

much more at the dealer!

That's the resistor block. Typically when that goes bad, you loose speeds, with typically only high speed working and if you switch to any other speed, the blower turns off. Maybe this one fails differently, because that isn't what is going on.

TDIDog · 02-03-2013, 10:52 AM

This can't be the resistor block because it only gets power and for some reason, it is getting power all the time and I should be able to shut it off by turning off the module.

rodboro · 02-03-2013, 05:32 PM

It has been over a year... i remember now, mine would turn off but when it was on it was only on high.....

TDIDog · 02-20-2013, 04:44 PM

I need to bump this up. The guy is getting tired of pulling the heater fuse. We know it's not the resistor block, so is it the EATC controller that is integral to the heater controls?

TDIDog · 02-20-2013, 05:45 PM

I guess I could pull the Controller then remove the wire going to signal the fan relay. If the fan goes off, replace the controller. If not there is a short to power somewhere.

RT · 02-20-2013, 06:09 PM

Have you checked the blower motor relay itself? Could it be fried in the engaged position? A lot of relays on our trucks are ground wire activated.

TDIDog · 02-20-2013, 08:55 PM

Quote:

Originally Posted by RT

Have you checked the blower motor relay itself? Could it be fried in the engaged position? A lot of relays on our trucks are ground wire activated.

Yeah, I swapped relays and then I found that there is constant power on the signal wire to that relay.