dinoroush

It is a blend door motor malfunction had one on my 2010 fx4

Mgizler

My understanding is that the blend door controls the hot/cold air mixture coming from the heater core area. And has no control over the fan speed.

The fan speed switch is separate and does have a resistor in the circuit that when it goes bad, will cause it to only operate on high, not get stuck there.

And the little servo part that people are reffering to is what controls the blend door via the temp switch.

If I had to guess, I would say that the fan speed switch mouth be faulty of take a closer look at the resistor.

shoot summ

I'm having this same issue on my '10 F150 Lariat, so is the general consensus still the motor resistor is the most likely culprit?

seadoons

I am the original poster. Yes, that was the problem and ford fixed it under warranty.

shoot summ

Thanks, mine is no longer under warranty so I am going to do it myself.

shoot summ

Thought I would update my experience so far.

I ordered the motor resistor, right part as indicated by all online resources. Fortunately I pulled my old one before I took it out of it's packaging.

So on on my 2010 Lariat the resistor is different than what is indicated online, even the bolt pattern is different.

mbingha

I've got a similar problem, my air will be normal, and then it will just go full blast. Sometimes it gets stuck there, other times it pulses, and sometimes it goes back to normal. I need to take it in, but since it only acts this way maybe 10% of the time I'm worried they won't be able to diagnose it. Is this likely a resistor issue too?

shoot summ

Thought I would post my results.

Turns out the auto climate control units require a different part only available from Ford.

Got the $60+ part, installed it and fixed the issue.

seadoons

Bringing this topic back to the top. I am the original poster from October 2011. I had it fixed sometime before March 2012. Here recently it has been acting up..running normally and then shoots to high speed. Or it will "pulse" the air speed - blowing slowly and it is like someone turns the switch full blast and then back down instantly. When it gets stuck on high speed I have been able to turn it off and back on and it "resets."


This morning for the first time it got stuck on low speed. I turned it off / on and got nothing. Blower doesn't even come on at all now.

Thoughts? Would a blown resistor cause this or did the resistor acting up finally burn up the blower motor?

BurntToast

I just had the exact same issue on my 2011. It was just fixed by the dealer under warranty and it was the resistor. It works fine now but it has only been a couple days.