No air from rear vents

[Dustin Gebhardt]

My rear blower would constantly fail to start. Like you, if I thumped it, it would turn on. I ended up buying a new blower (Rockauto) and this fixed my issue, although the new blower is louder than my old one (and that one was already noisy). I took apart my old blower and I'm waiting on a dreary winter day to replace the brushes.

 

[07navi]

I'm not sure where the resistor is on the rear blower. On the front blower it's mounted on the plenum box with the resistor coils in the airflow to cool them. The resistor consists of a series of open resistance windings that are switched in and out of the fan circuit to vary the motor voltage, controlling the speed. Since they get very hot from the current flow, they are not soldered but crimped together. Sometimes the crimps and corrosion get the better of them or the coils split and they open up, responding to the pounding that the OP described.

So if the resistor is anywhere near the rear motor, it should be checked before the motor is assumed to be the culprit. Locate it and fiddle with it to see if the internal connections are intermittent.

For all I know, newer models may be a different design -- electronic stuff that is not plagued by these problems. The last one I've dealt with was in a 2000, and that had conventional windings.

Here's a traditional blower resistor from a 2010 Explorer. The coils project into the plenum. See the crimps? The little semiconductor is a temperature fuse that opens if the thing overheats, as it may if airflow is obstructed.

Thanks, the ones later than about '07 are different. Probably some small improvements.

 

[drokmofo]

Thx for all the input 07navi and Trainmaster. I went ahead and purchased a new blower motor and resistor. I didn't inspect resistor prior to purchase

 

[drokmofo]

My rear blower would constantly fail to start. Like you, if I thumped it, it would turn on. I ended up buying a new blower (Rockauto) and this fixed my issue, although the new blower is louder than my old one (and that one was already noisy). I took apart my old blower and I'm waiting on a dreary winter day to replace the brushes.

Did you buy motorcraft or other brand blower motor?

 

[drokmofo]

Just replaced blower motor and inspected old resistor. Resistor matched the new 1 I purchased, just in case. So I left the old 1 in. All cold and blowing strong now. It was more of a pia taking the panels off to access the blower motor than anything else. 3 screws and the motor dropped out, popped in new and after maybe 30mns had everything buttoned back up. Thx to 07navi, Trainmaster, and DG. I appreciate your input.

 

[2015owner2015]

Where is the rear blower located?

I'm having the same issue. No rear fan hot or AC.