Checked mine yesterday, doesn't seem it changes the positive voltage as much as changing the resistance of the ground circuit. I can see all 4 different speeds, and while they seem alright it wouldn't be new car speeds. No debris in the casing or anything as well.

FD blower motors SUCK, those saying its good havent been in a newer car and felt how over powering and amazing the blower motors are in them. Years ago I spent some time on my blower motor. The voltage was totally fine, the grounding was totally fine. Its just not a good design.

Another area to think about - there are lots of connections in the system where air can escape thus also lowering the velocity of air coming out of the vents. Its all sealed with that foam stuff that is dry rotting and falling apart given its age.

Well we also have to think that maybe the design didn't need something as strong as the new cars today which are mostly 4 door large vehicles compared to the 2 door small inside of an fd. While the speed isn't fast, I haven't had any issues with the heating or cooling being in that small area.

The only issue I have had with my AC is that it seems to heat-soak badly if I've parked in the sun on a hot day. Takes a while after I start driving to cool down to a comfortable level, say 5 minutes or so. After that it has always been more than sufficient. And it's always been like that since I first got it in 1992.

Did you ever do anything to make it blow harder and did it work?

I rebuilt all my HVAC boxes a few years ago, and even replaced the foam at the joints in the ducting and wrapped insulation around the joints as well.

I haven't had AC since 2008 and my car is black outside, black inside. So it's pretty damn hot haha, even in Colorado. I'm so thankful I don't live somewhere hotter. I don't remember if mine ever heat soaked but I'm sure it did. I do remember it not working very well, and the previous owner said he had charged the system, so I assumed it was just a shitty system.

I feel like I want to test out the switch for speeds, resistor in the box that changes the values, and then motor. Although my car isn't with me at this time so just thinking of things to do.

Well from what I've read the resistor controls the speed on the first three settings, and the fourth setting is with the motor full speed no resistors. Which is why when the resistor goes bad the motor blows full speed on all settings. So if there's a way to wire in different resistors the first three settings can blow harder, but the fourth setting would require a different voltage or something. But I'm not good with any of this haha.

I'm wanting to get a replacement blower motor and see if a new motor helps out. Good thing is it looks like there's nothing too particular about our motor, many Mazda blowers (including the RX-8) look like they would work.

Dale

Hopefully that works well. I will say I have two FD blower motors here that I was testing with thinking perhaps mine had just went out. I tried hooking both of them up to direct battery outside of the box (ie: in my hands on the work bench) they both blew the same from what I could tell. I also swapped both into the blower box, they both delivered lame results that arent as good as modern cars.

Sweet. I'm gonna check out my buddy's 8 and see how well his works. Thanks Dale!

Good to know. I wonder if there was some difference between the different series, if they used different motors in series 7 and 8 or something. Or maybe just between different years.

in for info.

I'm ordering one of the RX8 motors and giving that a shot while I have all of my hvac assemblies out of the car. Will see how it goes.

Think I would have just tried finding a used rx8 one in the junkyard, probably plenty of those things there. But yes, looking to see your results for sure. I am starting to think something in my hvac box is jammed as the blender door moves when it wants, as well as the blower side isn't really attached the the rest since I pulled it out before.

Fair point. I didn't even think about pulling a used motor from a junkyard. Lots of places make motors for the RX8, and they are fairly affordable fortunately.

Not sure if it would cause your problem, but all the foam in mine was pretty much turned to crunchy dust, and all of the grease had also broken down for the most part. Lots of bits and pieces in the hvac system. I just cleaned up everything in the heater core assembly, but I still need to do the evaporator and blower motor assemblies, test all the servos, etc etc. Do not want to have to pull any of these assemblies again any time soon.

There is also a little linkage between one of the flappers on the main opening, and one of the flappers that's closer to the heater core. If that linkage is broken/disconnected/missing, it would result in one flapper doing its own thing. This thread shows the little linkage/actuator arm as part of the disassembly instructions.

https://www.rx7club.com/3rd-generati...hotos-1001759/

Agreed! Summer is coming soon and I can't drive a car in 100+ degrees without maximum blowing efficiency. (is that what she said?). If that rx8 blower works out you just added to my never ending to do list.

-groovin

The aftermarket RX8 blower came in the mail today. Here are my initial impressions.

It's definitely more or less a bolt on replacement for the stock motor. The electrical connector is the same, and the screw holes line up with the assembly. It seems to mate to the assembly fairly snug.

The only difference is that the aftermarket RX8 unit only has a square hole to vent the electrical motor to the passenger footwell, while the stock RX7 (and RX8 for that matter) have a tube that routes the motor vent to a spot inside the assembly to get fresh air. Honestly, I don't think it would be hard to put together a simple "adapter" so that the stock tubing could be used with the RX8 blower I have.

I hooked both up to 12v to compare. While the RX8 motor did seem to have a little bit more oomph, I can't say its a night and day difference. The airflow from the RX8 unit at full speed seemed a little better, but that could just be because its a brand new motor.

Other impressions:

The stock motor blades have a greater radius than the aftermarket RX8 blades, but not by much. The RX8 blades are taller, however.

When spun by hand the RX7 blades spin fairly freely, the RX8 one definitely feels to have some gearing.

The "bump" for the motor seems a little larger on the RX8 motor housing, but that's not necessarily an accurate indicator that the RX8 motor is bigger.

If I get a chance, I may try to grab a used OEM RX8 fan and see how it compares. All in all, the blower isn't super hard to change out while the assembly is in the car, so I think I will move forward with the RX8 unit since its brand new. I can always experiment with other blowers later if I want.

That's awesome details :icon_tup:

Once possibility if the shafts are the same size, you could swap the blower wheel.

Vince

Awesome!

I've been wanting to get one of these for a while -


That will measure wind speed, I think that would be a good way of testing fan functionality.

Dale

That thing has mixed reviews on the quality control, but for the price I will give it a shot. I'll put up another update once it arrives and I get a chance to test things out.

Based on the condition of all the foam seals, the foam on the flappers, how dirty the evaporator was, and all the other unpleasant things I have seen in my HVAC system as I go through it, I have to imagine that definitely contributes to the efficiency of the system. If the average RX7 hvac bits are in the same shape as mine were I can definitely see how that could contribute to a lot of lost air not making it to the vents, and in this case I'm not sure there is any blower on the market that's going to overcome that.

Just something to consider for anyone who doesn't know the condition of their hvac system and isn't happy with the performance.

Just FYI, if you close the vent under the steering wheel (crotch cooler) you will get a noticeable bump in air velocity.

Fiddled around with this some more, while reassembling my HVAC system after some thorough reconditioning.

So, I'm going to break this down into 4 categories, the stock fan with the stock wheel, the aftermarket RX8 fan with the aftermarket wheel, the OEM RX8 fan with the OEM RX8 wheel, the aftermarket RX8 fan with the stock wheel.

Before I get started, I just want to make it clear that fitting your stock wheel to an aftermarket wheel produced by 4seasons/unimotor is a pretty much a one way trip. Do so knowing that you will not easily be able to go back to using the stock wheel/Mazda shaft. The shafts are similar, but the 4seasons one is a bit large, so expanding the stock wheel shaft is required. I decided I could live with it, as there is a much large supply of 4Seasons motors than OEM RX7 wheels. YMMV.

Stock wheel:
There isn't much to say here. Its the stock wheel. It has the best fit and finish, and the plastic backing is much more satisfying to secure to the blower assembly. Mine was getting noticeably tired, and was thoroughly soaked in dark junk. It registered 15 meters/s on the cheap fan gizmo Dale linked.

Something to note that I didn't really know until after I had transplanted my wheel, is that the stock motor does seem somewhat serviceable. Undo the two screws at the top and it should with some effort pull out of the assembly. Mine had seen better days, and it's not unreasonable to assume that cleaning yours up and getting some new grease in there could give the motor a second wind.

Aftermarket RX8 with aftermarket wheel:
As noted above, the wheel 4seasons ships out for the RX8 is a little taller than the RX7 stock wheel, and has a very slightly smaller radius. The significance of this did not occur to me until I went to install it in my assembly to test the airflow, and turn it on. While it did fit just fine in the assembly, the extra height does cause some issues that aren't really visible, the extra height results in the fan getting stuck on the roof of the assembly.

Easy enough to fix, it is trivial to reduce the height slightly with a Dremel. The airflow with this motor registered a reasonable 18-19 meters/sec. You will also probably want to find a way to fit your stock vent hose to this unit, which just has a square opening. It's not super difficult to rig up an adapter, which is what I did.

Stock RX8 motor with stock RX8 wheel:
Theres some good and bad news here. The stock RX8 wheel is the same diameter as ours, and is a pretty dang close match. It appears to use the same shaft. The bad news is that it is still taller. I didn't go too far with this setup for the reasons I will note below, but I imagine with some height reduction this could be a feasible replacement for anyone who has a missing or damaged wheel, or wants to do some mad science experiments without sacrificing a stock one like I did.

The bad news is that the actual OEM motor assembly isn't going to be a direct fit without some finagling. I am attaching pictures, but the way the RX8 vents its motor causes fitment issues with our assemblies. You could probably use a dremel to make that one mounting point conform to our assembly, but it would take a bit of patience. With how cheap these are, might be worth the time though. No airflow readings since I couldn't install it to my blower assembly to get an accurate test.

Aftermarket RX8 motor, with stock RX7 wheel:
This is the abomination that I chose to go with. As mentioned above, the 4Seasons shaft is a little bigger than ours. With some creativity you can fit the stock wheel to it, but there isn't any going back to stock after this, not without some additional creativity. This seemed like the best of both worlds to me, a properly fitting wheel, and a brand new modern blower motor. If I did this again, I'd have probably tried to fit the stock RX8 wheel and reduce its height instead of use up the stock RX7 wheel, but I did this before the stock RX8 unit showed up in the mail.

Fitment almost as good as stock. You may need to use washers or get screws with larger heads to hold it on. Not sure if the screws holding my blower motor in were stock, but they seemed a bit small for this motor's mounting holes.

Speed registered as 20-22 meters/sec, the best out of the configurations I tested.

All electric motors are different, some wear faster and worse than others. Your mileage on this may vary. It was evident to me that my stock motor had a hard life, yours may be in better (or worse) shape. I could completely believe that when my stock motor rolled off the line, it had performance approximate to my shiny new aftermarket RX8 motor. Obviously in my case there appears to be around a 30% gain going to the new motor, so hopefully that should net a noticeable improvement.

This is probably as far as I will go spending time playing with these things for now. Unfortunately I still have a mile-long laundry list of work to do on my car and I have to move on.

However at the end of the day, I think replacing all of the crusty foam in my hvac system will probably be the biggest net improvement. End of long post, take this information as you will.

Awesome! Thanks so much for putting in the work!

I think you may have hit upon a winning combo.

FYI, trick for putting a fan with too large of a hole on a smaller shaft - wrap the shaft in Teflon tape to widen the shaft enough. Sounds weird, but my 99 spec fans have been on 93 motors on my radiator for years now with this method with zero problems, and those fans run harder and faster.

I wonder if there are other sources for motors and fan blades that may be even better, like other Mazda models or even another Japanese car brand. But for now we have a good solution.

Any recommendation on where to get that RX-8 fan motor?

Dale