12M3 How Deeply Buried the Blower Fan?

Today I cranked the heater fan up to notch 3 to get some quick heat into the cab, and heard the fan suck something in that sounded like maybe a leaf. So now the dash vibrates badly with any fan setting above 1, although it still works. How deeply buried is the fan? Is there a duct, cover, filter, etc. that will give me access to clean it out without too much grief? Looks like I will soon be the expert, just wondering if anyone else has been down this road and can give a few pointers.

Responding to my own question here ... how deeply buried?
Nigh to impossible. I think the blower must have been the
first thing into the dash on the assembly line and everything
else built around it. And to add injury to insult, Mazda
didn't do anything to keep mice from getting in through the
cowl. Maybe they don't have mice in Japan? The fuzzy paper
cloth that used to be the cabin air filter seems to have been
perfect nest-building material. Even the blower resistor board
has been chewed on, so I'll need to replace it if I want any
fan speed except full.

I armed myself with the factory service manual and spent most
of a day working my way into it. I'm pretty sure the guy who
wrote the manual has never done the jobs he is describing.
There are a lot of important details not mentioned.

For instance, they start out telling you to disconnect the
battery ground cable. Probably not necessary but good for
safety, right? But they fail to mention that the gear selector
needs to be in neutral to get the covers off, and you can't
get the selector out of park without power and stepping on
the brake pedal.

They also fail to mention several places where there are light
bulbs and other electrical stuff that will need to be undone
which has very short wires and not enough room to get fingers
in. It would be very easy to rip wires loose.

I have a couple screws that I have no clue what I will have to
do to get back together, one especially hard. It was one thing
to unscrew and let them fall out of the holes, but putting them
back is going to need at least three hands a light and a mirror
in a space about a half inch wide. May have to take the top off
the dashboard - I was hoping to avoid that. Or maybe superglue
a phillips bit, extensions and u-joints to the screw and let them
become a permanent part of the car.

I don't actually have the blower out. I've reached the point
where I find out if I can vacuum out the mess well enough to
not need to go deeper. That might be tomorrow's work depending
on what the weather does.

So tonite I still love the car, except for the HVAC which sucks.
Rant over for now.

I would try vacuum from the outside and compressed air from the inside before digging in deeper. Always try the easiest methods, first. Often, they are all you need.

Thanks for the reply. Vacuum session yesterday looks like it may have been sufficient.
Ordered parts today, big rip-off on the resistor prices but where else ya gonna go?
Will see if there's any vibration when new parts come, and if not then back together.
Don't know how I will get the thing they call the blower housing (which is really just
the external/internal air source flapper housing) back in - the screws were nearly
impossible to get out. A worry for another day, maybe next week.
- Rick in NW Ohio

Many years ago, many auto manufacturers offered "Factory Assembly Manuals" that had exploded drawings for just about everything. Screws, bolts, nuts, and all kinds of components and subassemblies were identified with factory part numbers. Rock Auto has quite a few exploded drawings in their website but just as it was back then, not every detail or "trick" was identified. Still, the ones I had were very handy. I once replaced a water heater with the help of such a manual.

So today the monsoon skies finally cleared and I got back to putting the 3 back together. The screw in the blower housing that I thought looked impossible was, but I got the other two back in, so at some point the concept of "good enough" comes into play.

The good news is that after vaccuming, new filters and resistor everything works. So I've started putting trim pieces back on.

Something will have to be done, though, with the fresh air path through the cowl, etc. to prevent a recurrance of the mouse problem. I pulled off the wipers and all the cowl pieces and was amazed (not pleasantly) with the design of it all.

Mazda did nearly everything short of providing free taxi service to make it easy for mice to get into the heater internals. The cowl grille and drain trays look nearly impossible to do anything with. A ray of hope is the hole in the firewall sheet metal. It has some formed edges that look like there might have been some kind of plan for a filter or mesh bonnet to snap
onto it that got forgotten in the rush to production. Anyone know of such a thing?

It's a job for another day, but my inventive mind is turning over ideas that may include hardware cloth, epoxy, brass rod, solder and sheet metal screws.

I think I can fix it, but it sucks that Mazda didn't deal with it up front. I vote for a big black mark against the HVAC design team on this one.

- Rick in soggy NW Ohio

I don't think the absence of built-in mouse barriers is unique to Mazda but I've owned 8 Mazdas over 38 years and never had a mouse problem. It could be that there weren't enough complaints over the years to warrant "corrective" action.
Are you sure you can't use some stainless steel wire mesh in a strategic location?

I was thinking brass because it can be cut, soldered, and shaped without much trouble, and the hole in the firewall looks like the best single "strategic location". The cowl grille and drain trays have too many openings too strangely shaped for wipers and washers and drains and related stuff.