A quick fix for the Mazda 3's blower fun

I currently live in a country where meaningful public transit is virtually non-existent. So, to get around, I rely on a 2005 Mazda 3 hatchback. It’s a simple car equipped with a 2.3L engine that is coupled to a 5 speed manual transmission. I’ve owned this car since 2017 and I love it so much. I’m pretty sure I’ll be driving it till it dies, and even when it dies someday, I’m convinced I will attempt an EV conversion.

In this post I’ll be sharing some information on how I fixed my car's faulty blower fan (the one responsible for blowing hot or cold air into the cabin). Perhaps this may serve as a testament of how easy this car is to work on. In several ways, this is going to be considered as one of those notes to self posts. By putting all this information in one place, I’ll probably save someone from having to dig through multiple threads of forum posts someday.

The Obligatory Disclaimer

Before I go on, I must say that I’m no mechanic. I really just love cars, and I like to work on them whenever I can. On that note, I'll like caution you of the potential to break your car if you follow the instructions in this post. Attempt the fixes described here at your own risk.

With the obligatory disclaimer out of the way, let's go through the steps required to fix this problem.

TLDL; Just the Steps

First, for those that just need the steps for the fix, here are the steps to attempt:

1. Open up the engine hood/bonnet and locate the fuse box.
2. Open the fuse box and locate the blower and starter relays.
3. Confirm that your blower relay is broken by swapping it with the starter’s. (Don’t worry, they are the same thing).
4. If the problem with your AC comes from the relay, the blower should now work when you turn it on.
5. If swapped relay fixed the problem, purchase a replacement for the broken relay, and you're good to go.
6. If these steps did not work, then I'm sorry you have to look for other solutions.

The following images illustrate where you can find objects of interest for this fix.

A rather hot summer

Early last summer, I noticed my air conditioning wasn’t working as expected. It would start blowing nicely then suddenly it would start to cycle on and off as I drove. Sometimes the situation was reversed; the unit would turn on until several minutes after I'd pushed the power button.

Interestingly, whenever the AC mysteriously shut itself off, it appeared things were still cooling (or heating) as expected. However, something inside the car was just preventing the treated air from getting into the cabin. This obstruction was more apparent when driving at highway speeds: I could feel a tiny stream of cold (or warm) air trickling through the vents. I suspected it had to do with fans because when the unit stops working, it's the fans that just go off.

Being an intermittent problem, I survived the summer and the fall by just ignoring it. I mean, I was fine when it worked and still was when it wasn’t—it was always just a mild discomfort. As we hit the winter months, however, things got worse and unbearable. Both in terms of the weather and the performance of the unit, there was a significant downturn. At this point I knew I needed to fix it, and I decided to attempt a DIY approach.

My limited knowledge in auto air conditioning led me on a journey through a myriad of long forum threads, guided by Google. On all forums, I noticed that anyone with the same problem was just advised to get their blower fan replaced. Of course, that became my plan until I realised it required stripping out the entire dashboard—a feat my limited skill and time will make impossible for a DIY approach.

An observant break?

There was something I had noticed, however. Whenever the unit shut itself off, I would hear a loud distinct click. Something that obviously sounded like a relay was going off. So, I popped the bonnet, looked into the fuse and relay box and found there was a dedicated relay for the blower fan. What even made it more interesting was the existence of a similar relay for the starter motor. I was quite excited by this discovery, and immediately put the starter relay in place of the blower. After this swap, the blower motor just whirred at all its speeds when the car was on. This was confirmation that the relay was the problem. I was quite proud of my diagnostic skills.

A cheap fix

Anyway, after a few bucks spent on a replacement, I was successful in my DIY fix without having to rip out my entire dashboard to replace the blower fan. What’s more interesting is that I saved myself a ton of money. So, if you are having a similar problem, try this out first before you go to the mechanic. It doesn’t take much time, and it may be worth your little while.