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How-to: Permanently fix the "no A/C on fan speed 2/3" problem

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Black Mica 02 P5
I'm having an interesting issue with my blow speeds (lol). It seems that the switch no longer alters the air flow. As I progress in speed, the air will blow but never like it used to; it doesn't, however, blow when my car is parked. I don't think it's an alternator issue because my lights, radio, interior lights, etc all still work with full power. My whole AC/Heat assembly is pretty wacky though. My temperature cable is disconnected (I can't figure out how to put it back on), the third switch (adjusting where the air is coming out--dash, feet, face, whatever) has never worked. Lots of issues and I went of on a tangent. Main issue: air speed, any ideas?
 
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Protege5
Hi!
I am new here, and just bought a Protg 5!
My a/c works in 1 but not 2, 3 and sometimes works in 4.
I am just wounding, is this still the best way to fix it?
Thanks for your help!
 

Hank3

Asian Persuasion <><
Contributor
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2010 Mazda5 GT
Hi!
I am new here, and just bought a Protg 5!
My a/c works in 1 but not 2, 3 and sometimes works in 4.
I am just wounding, is this still the best way to fix it?
Thanks for your help!
Best? That's subjective since there are a couple of other ways to fix the AC flickering issue. But I personally did this easier fix 2 years ago and it's still been working perfectly. Also did it to our previous 02 Protege and it was still working fine when we sold it last year.
 
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Protege5
Best? That's subjective since there are a couple of other ways. But I personally did this easier fix 2 years ago and it's still been working perfectly. Also did it to our previous 02 Protege and it worked fine right up until we sold it last year.
Just wounding why it stopped working?
 

Hank3

Asian Persuasion <><
Contributor
:
2010 Mazda5 GT
Just wounding why it stopped working?
I reread my post and used the wrong words. I meant to say it was still working when we sold it...don't know if it's still working since it's no longer our vehicle. Sorry :)
 
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Mazda Protege 2003
So I attempted this fix, and the ac does not flicker on 3,4 fan speed but, fan 1 doesn't turn on now and 2 flickers on and off as i drive.
Would someone please help me with this?
 
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Protege5
So I attempted this fix, and the ac does not flicker on 3,4 fan speed but, fan 1 doesn't turn on now and 2 flickers on and off as i drive.
Would someone please help me with this?
I did this fix and it all worked fine for me. Check your wires and make sure they are making a good connection.
 
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Mazda Protege 2003
i realized that i used the wrong blue/yellow wire and the wrong ground wire! (hand), is it necessary to disconnect battery while doing this job?
Thank You
 
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Mazda Protege 2003
Guys I made the connection to my AC properly and now its working 100%, no battery disconnect and its all wired up ready to take on the heat!
 
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2002 Mazda Protege5
I noticed my AC starting to exhibit this issue today. I'm no electronics expert, but I do have access to a bunch of 330 Ohm (and 10K) resistors. Would it be okay to use two 330s (or one 10K) instead of the 470/200 Ohm combo?
 

MadBiker

Luv my MP5!
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2002 Protege5
Hey guys, awesome writeup!! I've had this issue for a while now, but now the AC has deteriorated so far as to turn on even when I have it switched off.

i.e., even though its in the off position, I can hear the compressor kicking in and I can feel the extra load on the engine when driving. This happens with both the temperature dial in both cooling and heating modes.

Is the part beyond repair/this mod if this is happening?

Thanks for any info!!
 
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2002 Mazda Protege5
Hey team, my AC isnt working on 1/2/3 but lights up and blows on 4 but NO COLD AIR! i can feel the cold air come out LIGHTLY on setting 3, and when i turn in onto 4, i can def feel cold air blowing, but then it goes away.
 

323

lolmsp lolms3
Hey guys, awesome writeup!! I've had this issue for a while now, but now the AC has deteriorated so far as to turn on even when I have it switched off.

i.e., even though its in the off position, I can hear the compressor kicking in and I can feel the extra load on the engine when driving. This happens with both the temperature dial in both cooling and heating modes.

Is the part beyond repair/this mod if this is happening?

Thanks for any info!!

Wow you have the complete opposite problem lol. I would assume the switch itself is to blame and maybe a new HVAC control unit should fix it
 
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protege5
Clearly the original poster is of an engineering background, a well thought up work around. However out of curiousity, of those of you who have done this how has it held up long term? I'm sure the AC still works, basically the "acceptable range" for the compressor to engage after voltage drop, and understand that completely. So the AC light won't flicker anymore. In the engineering realm i understand what this does and why it works.

However the root cause that i've found real world (which doesn't always mesh with the engineering world) is that the contacts inside the fan switch are very thin, and the surface area of the contact point itself leaves a bit to be desired. When clean, everything works great. However over time dirt accumulates in there, which adds resistance to the circuit. This added resistance inside the fan switch itself is why the voltage drops as much as it does, to put the "AC Sense" circuit out of range, and turning off the compressor (AC light turns off). resistance adds heat, and enough resistance/heat melts connectors and wires. Normally, if the AC quits working, you'll stop and choose a different fan speed that DOES work. You don't LEAVE it on the setting that doesn't work (and if you do, you've likely got damaged/melted wires/connectors behind the fan switch).

While this work-around does increase the operating range of the AC sense circuit, and the AC doesn't cut out anymore, you're not fixing the increased resistance through the switch itself, which in many cases melts connectors/wires/etc at the back of the fan switch. So i'm curious to some of you who have done this, hows it work out long term? Any signs of melting parts because you're basically ignoring that it normally "wouldn't" work and forcing it to work anyway.
 
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