I have a 2003 Mazda 3 with a strange issue. The AC wasn't working, and I found that the relay wasn't closing when the button in the cabin was pressed. The actual relay is fine. I opened up the relay and was able to manually close it to engage the AC, which worked fine.

I'm having trouble finding the right service manual or schematic to figure out how to fix this. Does anyone have any ideas about where I could look next to fix this?

I'm having trouble finding the right service manual.


2 Answers 2


There are several possibilities:

So you need to check if the relay coil has an earth or ground - without a ground the coil won’t function and so the contacts won’t close

Test that the relay terminal getting a feed when you operate the switch - this may be a faulty switch or a blown fuse on the supply side etc

  • It does, and the AC fuse is still ok. Mar 17, 2019 at 20:19

As it turns out over the years the AC refrigerant had leaked out and the pressure in the lines was low enough that the AC would not engage. Manually shorting out the pressure switch caused the relay to engage and close the compressor clutch just fine. One AC recharge later and everything works properly.

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