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I have this odd issue where if my AC is on - usually on the face/feet setting and seemingly only if the fan is above 1, the AC will just turn itself off.

EDIT: it usually will be on for a while, it turns itself off after an arbitrary amount of time, usually not right away.

If I hit the AC button it doesn't always turn itself back on, but often I can get it to turn on if I turn the fan speed back to 0 and then back up to 1 and then 2.

Very odd, it 'feels' like an electrical short but I have no idea, and I'm not sure where to begin. I don't think the face/feet/windshield setting would actually change anything, and it happens rarely enough that it's difficult to troubleshoot properly - normally I just want to get the AC back on and I forget to take the opportunity to eliminate variables.

Anyone seen this before?

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  • Is it blowing as cold as usual? If not, that may be a thing to look at; It may be refrigerant being low, or a bad fan clutch or a regulator for the fan clutch. – yollooool Sep 4 '17 at 22:25
  • Yup, while the light is on it blows cold as usual. – Harv Sep 4 '17 at 22:55
  • It seems like something is causing the compressor clutch to disengage. Is the low-pressure icing up like here? – Zaid Sep 5 '17 at 7:25
  • @Zaid no.. not as far as I can tell. After driving with the AC on for a while, with a hot engine, I found a line that looked like in that photo and gingerly touched it ... cold unlike the rest of the engine. I imagine that's where the freezing would be if there were any? – Harv Sep 9 '17 at 8:39
  • Yes that's the line. What I suggest you do is inspect it when the issue recurs – Zaid Sep 9 '17 at 8:52
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My answer is based on 2 Mazda 3 models I owe and both of them had similar issue but the cause and the solutions were different.

  1. First Case - Automatic Climate Control in My 2010 Mazda 3 2.0 4 Door Sedan - The switches went bad and had to be replaced, I tried all the means to clean and repair it,but that did not help, the main problem was with the fan regulator. Though blower motor use to blow out air, but since the regulator went bad, it used to switch off the power to a/c clutch and compressor use to disengage. The problem was intermittent for a first couple of month, I waited until I found a cheaper deal from a local dealer and replaced the entire console. The symptoms were pretty similar to what you have described, added to that the A/c light on the on/off switch use to flicker.
  2. Second Case - Manual Climate Control in my 2011 Mazda 3 1.6 4 door Sedan - A/c clutch was the problem, it use to engage occasionally. Typically it use to work for a couple of minutes and go off automatically. The only difference from the first one was the a/c light did not flicker . I replaced the a/c clutch assembly.

What I would suggest is to perform a resistance test on your Fan Regulator. I could not find any guide around the amount of resistance in each level but obviously Level 4 should have the least resistance compared to Level 1. If any of the level comes infinite resistance, your switches are bad.

For A/C clutch assembly problems, again you can perform resistance test on the clutch coil, the resistance typically is around 1 ohm. If there is no resistance you will have to replace the clutch

Also as an added measure, check the evaporator temperature sensor fault code P0538 (not very sure though)

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