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[Solved] Weak air output from vents

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2013 Mazda 3 2.0 Skyactiv A/T

I have very weak air output from my vents. The temperature control seems to work fine (heat is hot, A/C is cold), it's just very weak output - maximum setting feels like what you would expect 4/10 to feel like. Some details:

  • Cabin air filter was recently changed (Bosch HEPA) and I double checked it is installed correctly. Unfortunately I threw away the previous OEM one, so I can't put that back in to compare if there is a difference.
  • It sounds like the blower motor is working, it gets louder as I turn it up - it's pretty loud on maximum, sounds like there should be a lot more output than there is.
  • The different vent modes work, so I don't think it's an actuator issue. Output is weak on all vent modes.

Any ideas what could be the problem? Thanks.

7 Answers
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Tried without the cabin air filter and the output felt like at least 3x stronger. A difference in output is to be expected with nothing restricting air flow, but I don't know how much of a difference is normal. I tested the entire range low to high and there was good gradual output throughout the range, so it seems like the issue could be that the filter I have (Bosch HEPA) might be very restrictive and probably not an issue with the blower motor/fan or clogged intake. I stopped by a mechanic for their opinion and they recommended I try a different filter before doing any deeper diagnostics, so I ordered an OE filter. Fingers crossed that's all it is!

Solved! The aftermarket Bosch filter was the problem. I put in a Denso OE-identical filter and now I get as much air output at 2/7 power as I was getting at 7/7 with the Bosch. The Bosch filter has HEPA filtration, so I guess it is extremely restrictive and was basically suffocating the air flow. I'll gladly trade a little less fine filtration for A/C that actually cools (I don't get how anyone could accept how restrictive the Bosch is). Thanks all for the suggestions; I'm so glad it was a simple (i.e. cheap) fix.

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make sure the blower intake isn't blocked with leaves and stuff

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I don't think the cabin air filter is the issue. As @mountainmanjoe  mentioned, make sure that the intake is clear and if you still have the issue, you may change the blower fan.

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Simple things first. Do what MM Joe said. If that isn't the problem, try removing the cabin air filter. Any better? If not, is the air coming out somewhere else, maybe the floor vents? If so, you have a stuck door or bad actuator. Maybe the duct became disconnected? Still no joy, check the blower motor. Maybe the squirrel cage is damaged or loose.

Good luck.

 

Thanks. Any concerns with operating without the cabin air filter (just for testing purposes)? The different vent modes seem to work, so I don't think it's an actuator issue.

No concerns. Won't hurt a thing.

Tried without the cabin air filter and the output felt like at least 3x stronger. A difference in output is to be expected with nothing restricting air flow, but I don't know how much of a difference is normal. I tested the entire range low to high and there was good gradual output throughout the range, so it seems like the issue could be that the filter I have (Bosch HEPA) might be very restrictive and probably not an issue with the blower motor/fan or clogged intake. I stopped by a mechanic for their opinion and they recommended I try a different filter before doing any deeper diagnostics, so I ordered an OE filter. Fingers crossed that's all it is!

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Is the air not cold enough or is the air output too low? 

If it's air temperature on the highway, check the belt and refrigerant. If it's air temperature at idle, there's a solenoid that likely failed (available for cheap on Amazon). 

If it's actual volume of air on the freeway, check the blower motor; if it's air output at idle, check the blower motor. 

Temperature works fine, A/C is plenty cold, it's just very low air output volume. I will start with the checking the intake and blower motor as others have suggested. Thanks.

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Usually, it's the last thing you changed that's the problem, in this case, the filter.  Pull it out and try switching it 180 degrees.  Many of them are directional in orientation and will not work if installed backwards.

Thanks. I bought the car a few months ago and only just started needing to use higher air settings, so I'm not sure it was working better before the cabin air filter replacement. I think I would've tested the A/C when I test drove it (also had it inspected by a mechanic), but I can't remember for sure. I double checked that the cabin air filter is installed in the correct direction. Someone else suggested I remove the cabin air filter and test the output to see if there is a difference.

Confirmed the problem was the aftermarket Bosch filter, apparently the HEPA filtration is extremely restrictive to air flow. I put in an OE-identical filter and now it's working great.

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Topic starter

Thanks all for the suggestions. I will start with looking into the cabin air filter, intake, and blower motor.

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