About 9 months ago I bought a used 2007 Pacifica for my wife that just rolled out of warranty at 36K miles. Of course after hitting that 36,000 milestone we realize the airflow in the rear of the car doesn't really work well, and may never have (I don't ever ride back there). Intuitively, the issue seems to be related to the electronics that controls the rear fan speed from what I can deduce. Regardless of how or where the rear fan speed is selected (auto, front, rear) we essentially get very low (fan works) or off. Since we're out of warranty and I can't prove the issue existed before 36K I'm willing to take a run at fixing this if I can get a little help from you all on what is wrong and what to do. I can do a lot of things on a car like water pumps, belts, most fluids, etc, but I've never needed to tackle electronics or HVAC, and now I've got both issues at once!

I have attempted to diagnose this through AllData and I'm thinking my rear HVAC control module might be bad as that is listed as controlling the blower speed. I'm not sure how much that part costs, but I'd like to be more sure of something like this before launching off and ordering parts. I appreciate everyone's input!

 

Is the heat/cooling system set to blow out the vents? Sounds silly but I was wondering why our Pacifica was not blowing out the rear 2nd and 3rd row vents while the system was in auto mode. Turns out the HVAC system was automaticaly setting the air flow to the floor only. Once we (manually) set it to blow out the vents it started to blow out the vents.

 

Well everyone, I'm man enough to admit when I've done something dumb, and I have. I thought that the booster fan in the rear of the car was working, but just stuck on it's lowest setting because some air was coming out, just not much. Realizing it's just a booster fan, some air should be coming out in the rear if the front is moving air. Sure enough, the speed of the air coming out of the rear was relative to the speed of the air selected for the front. So the fan, not the control module was the culprit. Luckily I thought to check the rear booster fan fuse before tearing the whole console apart, as that was the culprit. I hate being dumb, but I love easy .50 cent solutions!

 

The blown fuse I replaced for the rear blower (#34 10Amp) has already blown again. So now I'm getting concerned about what could be the cause of this. I'm at a lost on where to begin maybe someone has a suggestion? The blower motor does work in the few minutes it can run without blowing the fuse. Tearing out the interior of the car to get to wiring isn't a fun activity if it doesn't yield results...

 

Maybe the fan builds resistance and heat and as time goes by, the fuse blows. Have you seen the fan, if you spin it by hand, does it turn freely?

 

Did this issue ever get resolved? I'm also having an issue with the rear HVAC fuse (#34 10Amp) blowing after I replace it.

 

I ended up removing the motor (which required removing most of the center console) and couldn't see any problems with it. So, with nothing to lose, I just took the battery and put the leads right on the car battery. It wound up to full speed, smoked a little, and then ran fine. My guess is that something I couldn't see had wound around the motor shaft causing resistance and blown fuses. I replaced the fuse with a 15 amps fuse without a problem.

To save yourself some trouble, I'd pop in a 15 amp fuse, crank it up to high for a while, and see what happens. You might be able to put a 10 amp fuse back in, but I haven't bothered.

 

I put a 15 amp fuse in it an it seems good. I think I'll leave it in there for a while and see what happens. Thanks for the quick response.

 

For sure the fuse is #34. On all diagrams I can find that 10 Amp fuse is labeled as "spare"??